1. What is the phenomenon of radioactivity?
In 1896, French physicist Henri Becquerel accidentally placed a piece of uranium ore on a stack of undeveloped photographic plates wrapped in black paper. Having developed the plates, he was surprised to find black spots on them. Some unknown radiation was emitted from the uranium ore and left an image on the plates in the shape of a piece of ore. This radiation was called radioactive .
Thus, called radioactivity the property of nuclei to spontaneously (i.e., without any external influences) decay with the formation of new elements and the emission of a special kind of radiation called radioactive radiation.
2. What is the nature of alpha, beta and gamma radiation?
Rutherford discovered that the radiation of radioactive substances is divided by a magnetic field into a weakly deflected beam of positively charged particles (α - particles) and a strongly deflected beam of negatively charged particles (β - particles). Subsequently, Paul Willard discovered another component of radiation - γ rays, which are emitted by radioactive sources and are not deflected by a magnetic field.
Alpha rays represent a stream of nuclei of helium atoms. An alpha particle consists of two protons and two neutrons and, accordingly, has an atomic number of 2 and a mass number of 4. This was proven by direct experiments by Rutherford and Soddy. Thus, radon gas, emitting α-rays, creates helium atoms in a closed vessel, which is detected by the radiation spectrum.
The initial speed of alpha particles is of the order of (1.5 - 2.0)·10 7 m/s.
Beta rays represent a flow of electrons or positrons . This follows, in particular, from the fact that they have the same effect as cathode rays and have the same specific charge (e/m), measured when they move in electric and magnetic fields.
Gamma rays are short-wave electromagnetic radiation with a wavelength not exceeding 10 -2 nm and, therefore, are characterized by the highest photon energy E > 0.1 MeV.
Gamma radiation is not an independent type of radioactivity. It accompanies the processes of α- and β-decays and does not cause a change in the charge and mass number of nuclei. It has been established that γ-rays are emitted by daughter nuclei, which at the moment of their formation are excited and “drop” their energy in a time of 10 -13 – 10 -14 s.
3. What is the composition of the nucleus of an atom? How, using the periodic table D.I. Mendeleev, is it possible to determine the composition of the atomic nucleus of a particular chemical element?
4. What is the physics of the processes occurring during alpha and beta decays of nuclei?
With α - radioactivity, the nuclear charge decreases by 2 units (in units of proton charge) and the mass number - by 4 units. The decay product is placed in the periodic table two cells to the left of the original element. During b - decay, the mass number does not change, but the charge number increases by one - the element in the periodic table shifts one cell to the right.
5. What is the mechanism of the effect of radioactive radiation on matter?
As particles of radioactive radiation penetrate deep into the substance as a result of a series of subsequent collisions, the energy of the particles gradually decreases and, finally, when it reaches the level of thermal motion, ionization stops. In this case, the alpha particle attaches two electrons (from the free electrons present in every substance) and turns into a helium atom. The negative β-particle (electron) remains in a free state or is attached to any atom or ion of the substance. A gamma photon is absorbed by the electron with which it last collided.
6. What is the harmful effect of radioactive radiation on biological objects?
The harmful effects of nuclear radiation are associated with the ionization and excitation of atoms of living cells of the body due to the Compton effect, bremsstrahlung, photoelectric effect and some other effects. Individual components of a living cell are changed or destroyed by this ionization, and the products of decomposition begin to act as poisons. Examples of destruction in the body are the destruction of chromosomes, swelling of cell nuclei and the cells themselves, changes in the permeability of cell membranes, etc. The most sensitive cells are those of the bone marrow, lymph glands, oral cavity and intestines, genitals, hair follicles and skin.
The greater the ionizing ability of the particles, the less their penetrating ability. Thus, an α-particle, when traveling in air, produces up to 40 thousand pairs of ions on a path of 1 cm. A beta particle at the same distance produces 40–50 pairs of ions, and γ-photons – from 10 to 250 pairs of ions. In accordance with this, a thin layer of any substance, for example, a paper screen, can serve as protection against α-particles. Plexiglas or an aluminum screen several millimeters thick can serve as protection against β-radiation. To protect against γ-radiation, thick layers of earth, concrete or heavy metals are used, for example, a lead screen several centimeters thick.
7. What can you tell us about the prevalence of radioactive isotopes in nature?
In conclusion, we note that radioactive isotopes are widely used in medicine for therapeutic, diagnostic and research purposes. For example, radioactive cobalt is used to treat malignant tumors as a γ-emitter. Radioactive isotopes of phosphorus, emitting β-particles, are used to treat blood diseases, radioactive iodine () - to treat the thyroid gland.
8. Give the concepts of exposure and absorbed radiation doses, as well as their powers. In what units are they measured?
Dose rate (irradiation intensity) is the increment of the corresponding dose under the influence of a given radiation per unit of time. It has the dimension of the corresponding dose (absorbed, exposure, etc.) divided by a unit of time. The use of various special units is allowed (for example, Sv/hour, rem/min, mSv/year, etc.).
Radiation dose - in physics and radiobiology - a value used to assess the impact of ionizing radiation on any substances, tissues and living organisms.
Exposure dose
The main characteristic for the interaction of ionizing radiation and the environment is the ionization effect. In the initial period of development of radiation dosimetry, it was most often necessary to deal with X-ray radiation propagating in the air. Therefore, the degree of ionization of the air in X-ray tubes or devices was used as a quantitative measure of the radiation field. A quantitative measure based on the amount of ionization of dry air at normal atmospheric pressure, which is quite easy to measure, is called exposure dose.
Exposure dose determines the ionizing ability of X-rays and gamma rays and expresses the radiation energy converted into the kinetic energy of charged particles per unit mass of atmospheric air. Exposure dose is the ratio of the total charge of all ions of the same sign in an elementary volume of air to the mass of air in this volume.
The SI unit of exposure dose is the coulomb divided by kilogram (C/kg). The non-systemic unit is the roentgen (R). 1 C/kg = 3876 RUR.
Absorbed dose
When expanding the range of known types of ionizing radiation and the areas of its application, it turned out that the measure of the impact of ionizing radiation on matter cannot be easily determined due to the complexity and diversity of the processes occurring in this case. An important one, which gives rise to physicochemical changes in the irradiated substance and leads to a certain radiation effect, is the absorption of the energy of ionizing radiation by the substance. As a result, the concept of absorbed dose arose. The absorbed dose shows how much radiation energy is absorbed per unit mass of any irradiated substance and is determined by the ratio of the absorbed energy of ionizing radiation to the mass of the substance.
The unit of measurement of absorbed dose in the SI system is the gray (Gy). 1 Gy is the dose at which 1 J of ionizing radiation energy is transferred to a mass of 1 kg. The extrasystemic unit of absorbed dose is the rad. 1 Gy=100 rad.
Equivalent dose (biological dose)
The study of individual consequences of irradiation of living tissues has shown that, with the same absorbed doses, different types of radiation produce unequal biological effects on the body. This is due to the fact that a heavier particle (for example, a proton) produces more ions per unit path in the tissue than a lighter particle (for example, an electron). For the same absorbed dose, the higher the radiobiological destructive effect, the denser the ionization created by the radiation. To take this effect into account, the concept of equivalent dose was introduced. The equivalent dose is calculated by multiplying the value of the absorbed dose by a special coefficient - the coefficient of relative biological effectiveness (RBE) or quality coefficient.
The SI unit of dose equivalent is the sievert (Sv). The value of 1 Sv is equal to the equivalent dose of any type of radiation absorbed in 1 kg of biological tissue and creating the same biological effect as the absorbed dose of 1 Gy of photon radiation. The non-systemic unit of measurement of equivalent dose is the rem (before 1963 - the biological equivalent of an x-ray, after 1963 - the biological equivalent of a rad - Encyclopedic Dictionary). 1 Sv = 100 rem.
Effective dose
Effective dose (E) is a value used as a measure of the risk of long-term consequences of irradiation of the entire human body and its individual organs and tissues, taking into account their radiosensitivity. It represents the sum of the products of the equivalent dose in organs and tissues by the corresponding weighting factors.
Some human organs and tissues are more sensitive to the effects of radiation than others: for example, at the same equivalent dose, cancer is more likely to occur in the lungs than in the thyroid gland, and irradiation of the gonads is especially dangerous due to the risk of genetic damage. Therefore, radiation doses to different organs and tissues should be taken into account with different coefficients, which is called the radiation risk coefficient. By multiplying the equivalent dose value by the corresponding radiation risk coefficient and summing over all tissues and organs, we obtain an effective dose reflecting the total effect on the body.
Weighted coefficients are established empirically and calculated in such a way that their sum for the entire organism is unity. The effective dose units are the same as the equivalent dose units. It is also measured in sieverts or rem.
Effective and equivalent dose- these are standardized values, that is, values that are a measure of damage (harm) from the effects of ionizing radiation on a person and his descendants [source not specified 361 days]. Unfortunately, they cannot be directly measured. Therefore, operational dosimetric quantities have been introduced into practice, unambiguously determined through the physical characteristics of the radiation field at a point, as close as possible to the standardized ones. The main operational quantity is the ambient dose equivalent (synonyms - ambient dose equivalent, ambient dose).
Ambient dose equivalent H*(d)- dose equivalent, which was created in the ICRU (International Commission on Radiation Units) spherical phantom at a depth d (mm) from the surface along a diameter parallel to the direction of radiation, in a radiation field identical to that considered in composition, fluence and energy distribution, but monodirectional and homogeneous, that is, the ambient dose equivalent H*(d) is the dose that a person would receive if he were at the place where the measurement is being taken. The unit of ambient dose equivalent is the sievert (Sv).
9. Characterize the effect of ionizing radiation on air under normal conditions, if the exposure dose rate is 1 R/s.
10. What are the measures to protect against radioactive radiation?
The shorter the contact time your body has with radioactive substances, the better for you and your health. If this is not yet possible, we take the following measures: we do not leave the premises, we do wet (namely wet!) cleaning 2-3 times a day;
· We shower as often as possible (especially after going outside), and wash things. Regular rinsing of the mucous membranes of the nose, eyes and throat with saline solution is not so important, since a much larger amount of radionuclides enters during breathing;
· to protect the body from radioactive iodine-131, it is enough to lubricate a small area of skin with medical iodine. According to doctors, this simple method of protection lasts for a month;
· if you have to go outside, it is better to wear light-colored clothing, preferably cotton and damp. It is recommended to wear a hood and a baseball cap on your head at the same time;
· in the first few days you need to be wary of radioactive fallout, that is, “lay low and sit out.”
>> Alpha, beta and gamma radiation
§ 99 ALPHA, BETA AND GAMMA RADIATIONS
After the discovery of radioactive elements, research began on the physical nature of their radiation. In addition to Becquerel and the Curies, Rutherford took up this task.
The classic experiment that made it possible to detect the complex composition of radioactive radiation was as follows. The radium preparation was placed at the bottom of a narrow channel in a piece of lead. There was a photographic plate opposite the channel. The radiation emerging from the channel was affected by a strong magnetic field, the induction lines of which were perpendicular to the beam (Fig. 13.6). The entire installation was placed in a vacuum.
In the absence of a magnetic field, one dark spot was detected on the photographic plate after development exactly opposite the channel. In a magnetic field, the beam split into three beams. The two components of the primary flow were deflected in opposite directions. This indicated that these radiations had electrical charges of opposite signs. In this case, the negative component of the radiation was deflected by the magnetic field much more strongly than the positive one. The third component was not deflected by the magnetic field at all. The positively charged component is called alpha rays, the negatively charged component is called beta rays, and the neutral component is called gamma rays (-rays, -rays, -rays).
These three types of radiation differ greatly in penetrating ability, that is, in how intensely they are absorbed by various substances. -rays have the least penetrating ability. A layer of paper about 0.1 mm thick is already opaque for them. If you cover a hole in a lead plate with a piece of paper, then no spot corresponding to -radiation will be found on the photographic plate.
Much less is absorbed when passing through matter - rays. The aluminum plate completely stops them only with a thickness of a few millimeters. .-rays have the greatest penetrating ability.
The intensity of absorption of -rays increases with increasing atomic number of the absorbent substance. But a layer of lead 1 cm thick is not an insurmountable obstacle for them. When β-rays pass through such a layer of lead, their intensity weakens only by half. The physical nature of -, - and - rays is obviously different.
Gamma rays. In their properties, -rays are very similar to X-rays, but their penetrating power is much greater than that of X-rays. This suggested that the -rays were electromagnetic waves. All doubts about this disappeared after the diffraction of β-rays on crystals was discovered and their wavelength was measured. It turned out to be very small - from 10 -8 to 10 -11 cm.
On the scale of electromagnetic waves, -rays directly follow X-rays. The speed of propagation of y-rays is the same as that of all electromagnetic waves - about 300,000 km/s.
Beta rays. From the very beginning, - and - rays were considered as streams of charged particles. It was easiest to experiment with -rays, since they are more strongly deflected in both magnetic and electric fields.
The main task of the experimenters was to determine the charge and mass of the particles. When studying the deflection of -particles in electric and magnetic fields, it was found that they are nothing more than electrons moving at speeds very close to the speed of light. It is important that the velocities of -particles emitted by any radioactive element are not the same. There are particles with very different speeds. This leads to the expansion of the beam of particles in a magnetic field (see Fig. 13.6).
Alpha particles. It was more difficult to find out the nature of -particles, since they are less strongly deflected by magnetic and electric fields. Rutherford finally managed to solve this problem. He measured the ratio of a particle's charge q to its mass m by its deflection in a magnetic field. It turned out to be approximately 2 times less than that of a proton - the nucleus of a hydrogen atom. The charge of a proton is equal to the elementary one, and its mass is very close to the atomic mass unit 1. Consequently, the y-particle has a mass equal to two atomic mass units per elementary charge.
But the charge of the particle and its mass remained, nevertheless, unknown. It was necessary to measure either the charge or the mass of the particle. With the advent of the Geiger counter, it became possible to measure charge more easily and accurately. Through a very thin window, particles can penetrate into the counter and be registered by it.
Rutherford placed a Geiger counter in the path of the particles, which measured the number of particles emitted by a radioactive drug over a certain time. Then he replaced the counter with a metal cylinder connected to a sensitive electrometer (Fig. 13.7). Using an electrometer, Rutherford measured the charge - particles emitted by the source inside the cylinder in the same time (the radioactivity of many substances almost does not change with time). Knowing the total charge of the -particles and their number, Gezerfod determined the ratio of these quantities, i.e., the charge of one -particle. This charge turned out to be equal to two elementary ones.
Thus, he established that the y-particle has two atomic mass units for each of the two elementary charges. Therefore, there are four atomic mass units per two elementary charges. The helium nucleus has the same charge and the same relative atomic mass. It follows from this that a particle is the nucleus of a helium atom.
Not content with the achieved result, Rutherford then proved through direct experiments that it is helium that is formed during radioactive decay. Collecting -particles inside a special container for several days, he, using spectral analysis, was convinced that helium was accumulating in the vessel (each -particle captured two electrons and turned into a helium atom).
1 Atomic mass unit (a.s.m.) rapia 1/12 the mass of a carbon atom; 1 a. e.m. 1.66057 10 -27 kg.
During radioactive decay, -rays (nuclei of a helium atom), -rays (electrons) and -rays (short-wave electromagnetic radiation) are produced.
Why did it turn out to be much more difficult to find out the nature of -rays than in the case of -rays?
Myakishev G. Ya., Physics. 11th grade: educational. for general education institutions: basic and profile. levels / G. Ya. Myakishev, B. V. Bukhovtsev, V. M. Charugin; edited by V. I. Nikolaeva, N. A. Parfentieva. - 17th ed., revised. and additional - M.: Education, 2008. - 399 p.: ill.
Physics lesson planning online, tasks and answers by grade, physics homework for grade 11 download
Lesson content lesson notes supporting frame lesson presentation acceleration methods interactive technologies Practice tasks and exercises self-test workshops, trainings, cases, quests homework discussion questions rhetorical questions from students Illustrations audio, video clips and multimedia photographs, pictures, graphics, tables, diagrams, humor, anecdotes, jokes, comics, parables, sayings, crosswords, quotes Add-ons abstracts articles tricks for the curious cribs textbooks basic and additional dictionary of terms other Improving textbooks and lessonscorrecting errors in the textbook updating a fragment in a textbook, elements of innovation in the lesson, replacing outdated knowledge with new ones Only for teachers perfect lessons calendar plan for the year; methodological recommendations; discussion program Integrated LessonsThe concept of “radiation” includes the entire range of electromagnetic waves, as well as electric current, radio waves, and ionizing radiation. With the latter, the physical state of atoms and their nuclei changes, turning them into charged ions or products of nuclear reactions. The smallest particles have energy, which is gradually lost when interacting with structural units. As a result of the movement, the substance through which the elements penetrate becomes ionized. The penetration depth is different for each particle. Because of its ability to change substances, radioactive light is harmful to the body. What types of radiation exist?
Corpuscular emission. Alpha particles
This type is a flow of radioactive elements whose mass is different from zero. An example is alpha and beta radiation, as well as electron, neutron, proton and meson. Alpha particles are atomic nuclei that are emitted when certain radioactive atoms decay. They consist of two neutrons and two protons. Alpha radiation comes from the nuclei of helium atoms, which are positively charged. Natural emission is typical for unstable radionuclides of the thorium and uranium series. Alpha particles exit the nucleus at speeds of up to 20 thousand km/sec. Along the path of movement, they form a strong ionization of the medium, tearing electrons from the orbits of atoms. Ionization by rays leads to chemical changes in the substance, as well as to disruption of its crystal structure.
Characteristics of alpha radiation
Rays of this type are alpha particles with a mass of 4.0015 atomic units. The magnetic moment and spin are zero, and the particle charge is double the elementary charge. The energy of alpha rays is in the range of 4-9 MeV. Ionizing alpha radiation occurs when an atom loses its electron and becomes an ion. The electron is knocked out due to the large weight of alpha particles, which are almost seven thousand times larger than it. As the particles pass through an atom and break off each negatively charged element, they lose their energy and speed. The ability to ionize matter is lost when all the energy is spent and the alpha particle is converted into a helium atom.
Beta radiation
It is a process in which electrons and positrons are produced by beta decay of elements ranging from the lightest to the heaviest. Beta particles cooperate with the electrons of atomic shells, transfer some of the energy to them and tear them out of orbit. In this case, a positive ion and a free electron are formed. Alpha and beta radiation have different speeds of movement. So, for the second type of rays it approaches the speed of light. Beta particles can be absorbed using a 1 mm thick layer of aluminum.
Gamma rays
They are formed during the decomposition of radioactive nuclei, as well as elementary particles. This is a short-wave type of electromagnetic radiation. It is formed when a nucleus transitions from a more excited energy state to a less excited one. It has a short wavelength and therefore has high penetrating power, which can cause serious harm to human health.
Properties
Particles that are formed during the decay of elemental nuclei can interact with the environment in different ways. This connection depends on the mass, charge, and energy of the particles. The properties of radioactive radiation include the following parameters:
1. Penetrating ability.
2. Ionization of the medium.
3. Exothermic reaction.
4. Impact on photographic emulsion.
5. The ability to cause the glow of luminescent substances.
6. With prolonged exposure, chemical reactions and breakdown of molecules are possible. For example, the color of an object changes.
The listed properties are used in detecting radiation due to the inability of humans to detect them with their senses.
Radiation sources
There are several reasons for particle emissions. These can be terrestrial or space objects that contain radioactive substances, technical devices that emit ionizing radiation. Also, the causes of the appearance of radioactive particles can be nuclear installations, control and measuring devices, medical supplies, and the destruction of radiation waste storage facilities. Hazardous sources are divided into two groups:
- Closed. When working with them, radiation does not penetrate into the environment. An example would be radiation technology at nuclear power plants, as well as equipment in the X-ray room.
- Open. In this case, the environment is exposed to radiation. Sources can be gases, aerosols, radioactive waste.
The elements of the series uranium, actinium and thorium are naturally occurring radioactive elements. When they decay, alpha and beta particles are emitted. The sources of alpha rays are polonium with atomic weights 214 and 218. The latter is a decay product of radon. This is a poisonous gas in large quantities that penetrates from the soil and accumulates in the basements of houses.
Sources of high-energy alpha radiation are a variety of charged particle accelerators. One such device is a phasotron. It is a cyclic resonant accelerator with a constant control magnetic field. The frequency of the accelerating electric field will vary slowly with period. The particles move in an unwinding spiral and are accelerated to an energy of 1 GeV.
Ability to penetrate substances
Alpha, beta, and gamma radiation have a certain range. Thus, the movement of alpha particles in the air is several centimeters, while beta particles can travel several meters, and gamma rays can travel up to hundreds of meters. If a person has experienced external alpha radiation, the penetration power of which is equal to the surface layer of the skin, then he will be in danger only in the case of open wounds on the body. Eating food irradiated with these elements causes severe harm.
Beta particles can penetrate the body only to a depth of no more than 2 cm, but gamma particles can cause irradiation of the entire body. The rays of the last particles can only be stopped by concrete or lead slabs.
Alpha radiation. Impact on humans
The energy of these particles formed during radioactive decay is not enough to overcome the initial layer of skin, so external irradiation does not harm the body. But if the source of the formation of alpha particles is an accelerator and their energy reaches above tens of MeV, then a threat to the normal functioning of the body is present. Direct penetration of a radioactive substance into the body causes enormous harm. For example, through inhalation of poisoned air or through the digestive tract. Alpha radiation can, in minimal doses, cause a person to develop radiation sickness, which often ends in the death of the victim.
Alpha rays cannot be detected using a dosimeter. Once in the body, they begin to irradiate nearby cells. The body forces cells to divide faster to fill the gap, but those born again are again exposed to harmful effects. This leads to loss of genetic information, mutations, and the formation of malignant tumors.
Permissible exposure limits
The standard of ionizing radiation in Russia is regulated by the “Radiation Safety Standards” and the “Basic Sanitary Rules for Working with Radioactive Substances and Other Sources of Ionizing Radiation.” According to these documents, exposure limits are developed for the following categories:
1. "A". This includes employees who work with a radiation source on a permanent basis or temporarily. The permissible limit is calculated as an individual equivalent dose of external and internal radiation per year. This is the so-called maximum permissible dose.
2. "B". The category includes the portion of the population that may be exposed to radiation sources because they live or work near them. In this case, the permissible dose per year is also calculated, at which health problems will not occur for 70 years.
3. "B". This type includes the population of a region, region or country exposed to radiation. Limitation of exposure occurs through the introduction of standards and control of radioactivity of objects in the environment, harmful emissions from nuclear power plants, taking into account dose limits for the previous categories. The impact of radiation on the population is not subject to regulation, since exposure levels are very low. In cases of radiation accidents in the regions, all necessary safety measures are applied.
Security measures
Alpha radiation protection is not a problem. Radiation rays are completely blocked by a thick sheet of paper and even human clothing. The danger arises only from internal exposure. To avoid it, personal protective equipment is used. These include overalls (overalls, moleskin helmets), plastic aprons, oversleeves, rubber gloves, and special shoes. To protect the eyes, plexiglass shields are used, dermatological products (pastes, ointments, creams), and respirators are also used. Enterprises are resorting to collective protection measures. As for protection from radon gas, which can accumulate in basements and bathrooms, in this case it is necessary to frequently ventilate the premises and insulate the basements from the inside.
The characteristics of alpha radiation lead us to the conclusion that this type has a low throughput and does not require serious protective measures during external exposure. These radioactive particles cause great harm when they penetrate into the body. Elements of this type extend over minimal distances. Alpha, beta, and gamma radiation differ from each other in their properties, penetrating ability, and impact on the environment.
Theory: Radioactivity is a change in the composition of the atomic nucleus.
Alpha radiation
- flow of helium nuclei (flow of positively charged particles)
With alpha radiation, the mass number decreases by 4, and the charge number decreases by 2.
Displacement rule: with alpha radiation, an element is shifted two cells to the beginning of the periodic table. 
beta radiation
- flow of electrons (flow of negatively charged particles)
With beta radiation, the mass number does not change, the charge number increases by 1.
Shift rule: Beta radiation causes an element to shift one cell toward the end of the periodic table. 
gamma radiation - electromagnetic wave of high frequency and penetrating ability.
When α and β particles enter a magnetic field, a force acts on them, deflecting them to the side. The mass of alpha particles is greater than the mass of beta particles, so they are deflected less. The direction of the force is along. γ rays do not bow out. 
Half-life is the period of time during which half the original number of radioactive nuclei decays. But the half-life law is valid only for a large number of atoms. Since it is impossible to predict when a single nucleus will decay, but for a large number of particles this law is valid. 
When emitting a γ-quantum
1) the mass and charge numbers of the nucleus do not change
2) the mass and charge numbers of the nucleus increase
3) the mass number of the nucleus does not change, the charge number of the nucleus increases
4) the mass number of the nucleus increases, the charge number of the nucleus does not change
Solution: Gamma radiation is an electromagnetic wave, it does not affect the composition of the atomic nucleus, the mass and charge numbers of the nucleus do not change.
Answer: 1
OGE assignment in physics (fipi): Below are the equations for two nuclear reactions. Which one is a β-decay reaction? 
1) only A
2) only B
3) both A and B
4) neither A nor B
Solution: Beta decay is accompanied by the emission of electrons; there is no electron in any of the reactions.
Answer: 4
OGE assignment in physics (fipi): Below are the equations for two nuclear reactions. Which one is a β-decay reaction? 
1) only A
2) only B
3) both A and B
4) neither A nor B
Solution: beta decay is accompanied by the emission of electrons, in both reactions an electron is formed..
Answer: 3
OGE assignment in physics (fipi): Using the fragment of the Periodic Table of Chemical Elements presented in the figure, determine which isotope of the element is formed as a result of the alpha decay of bismuth.
1) lead isotope
2) thallium isotope
3) polonium isotope
4) astatine isotope
Solution: as a result of alpha decay, the atomic number of the element will decrease by 2, from bismuth (Z=83) the element will turn into an isotope of thallium (Z=81)
Answer: 2
OGE assignment in physics (fipi): Using a fragment of the Periodic Table of Chemical Elements presented in the figure, determine which isotope of the element is formed as a result of the electronic beta decay of bismuth.
1) lead isotope
2) thallium isotope
3) polonium isotope
4) astatine isotope
Solution: as a result of beta decay, the atomic number of the element will increase by 1, from bismuth (Z=83) the element will turn into an isotope of polonium (Z=84)
Answer: 3
OGE assignment in physics (fipi): A container containing a radioactive substance is placed in a magnetic field, causing a beam of radioactive radiation to split into three components (see figure). 
Component (3) corresponds to
1) gamma radiation
2) alpha radiation
3) beta radiation
4) neutron radiation
Solution: Let's use the rule of the left hand, the flow of particles is directed upward, point four fingers upward. The magnetic field lines are directed into the plane of the screen (away from us), the magnetic field lines are directed into the palm, the thumb bent 90 o shows that positively charged particles are deflected to the left. Component (3) deviated to the right, therefore these particles are negatively charged. Beta radiation is a stream of negatively charged particles.
Method 2: Component (3) deviates more than component (1), which means (3) has less mass. An electron has a mass less than that of a helium nucleus, which means component (3) is a flow of electrons (gamma radiation)
Answer: 3
OGE assignment in physics (fipi): The half-life is the period of time during which half the original number of radioactive nuclei decays. The figure shows a graph of changes in the number N of radioactive nuclei over time t. 
According to the graph, the half-life is
1) 10 s
2) 20 s
3) 30 s
4) 40 s
Solution: At the time t 1 = 20 seconds there were N 1 = 40 10 6 radioactive nuclei, half of the radioactive nuclei N 2 = 20 10 6 had decayed by the time t 2 = 40 seconds, therefore the half-life T = t 2 - t 1 = 40 - 20 = 20 s, the graph shows that every 20 seconds half of the remaining atoms decay.
Answer: 2
OGE assignment in physics 2017: During alpha decay of a nucleus, its charge number
1) decreases by 2 units
2) decreases by 4 units
3) increases by 2 units
4) increases by 4 units
Solution: During alpha decay of a nucleus, its charge number decreases by 2 units, because a helium nucleus with a charge of +2e flies out.
Answer: 1
OGE assignment in physics (fipi): When studying natural radioactivity, three types of radiation were discovered: alpha radiation (a stream of alpha particles), beta radiation (a stream of beta particles) and gamma radiation. What are the sign and magnitude of the charge of beta particles?
1) positive and equal in modulus to the elementary charge
2) positive and equal in modulus to two elementary charges
3) negative and equal in modulus to the elementary charge
4) beta particles have no charge
Solution: beta radiation is a flow of electrons, the charge of the electron is negative and equal in magnitude to the elementary charge.
Answer: 3
OGE assignment in physics (fipi): Below are the equations for two nuclear reactions. Which one is an α-decay reaction? 
1) only A
2) only B
3) both A and B
4) neither A nor B
Solution: Alpha decay produces helium nuclei; of the two reactions, only the second produces a helium nucleus.
Answer: 2
OGE assignment in physics (fipi): A radioactive drug is placed in a magnetic field. This field may deviate
A. α-rays.
B. β-rays.
The correct answer is
1) only A
2) only B
3) both A and B
4) neither A nor B
Solution: a moving charged particle entering a magnetic field is deflected, α-rays and β-rays have a charge, therefore, they will be deflected in the magnetic field.
Answer: 3
OGE assignment in physics (fipi): What types of radioactive radiation passing through a strong magnetic field are not deflected?
1) alpha radiation
2) beta radiation
3) gamma radiation
4) alpha radiation and beta radiation
Solution: a moving charged particle entering a magnetic field is deflected; gamma rays have no charge, so they are not deflected in a magnetic field.
Answer: 3
OGE assignment in physics (fipi): Natural radioactivity of the element
1) depends on the ambient temperature
2) depends on atmospheric pressure
3) depends on the chemical compound that contains a radioactive element
4) does not depend on the listed factors
Answer: 4
OGE assignment in physics (fipi): Using a fragment of the Periodic Table of Chemical Elements presented in the figure, determine the composition of the fluorine nucleus with mass number 19.
1) 9 protons, 10 neutrons
2) 10 protons, 9 neutrons
3) 9 protons, 19 neutrons
4) 19 protons, 9 neutrons
Solution: the number of protons is equal to the atomic number of the element, fluorine has 9 protons, to find the number of neutrons from the mass number we subtract the charge number 19-9 = 10.
Answer: 1
OGE assignment in physics (fipi): Which of the three types of radiation - α, β or γ - has the least penetrating power?
1) α
2) β
3) γ
Solution: Of the three types of radiation, the largest are α-particles, helium nuclei are larger than electrons and gamma rays, therefore, it is more difficult for them to pass through an obstacle.
Answer: 1
Which of the three types of radiation - α, β or γ - has the greatest penetrating power?
1) α
2) β
3) γ
4) the penetrating ability of all types of radiation is the same
alpha, beta (a group of corpuscular radiation), gamma radiation (a group of wave radiation).
Corpuscular are streams of invisible elementary particles having mass and diameter. Wave radiations are of a quantum nature. These are electromagnetic waves in the ultrashort wave range.
Alpha radiation is a stream of alpha particles propagating with an initial speed of about 20 thousand km/s. Their ionizing ability is enormous, and since each act of ionization requires a certain energy, their penetrating ability is insignificant: the path length in air is 3-11 cm, and in liquid and solid media - hundredths of a millimeter. A sheet of thick paper completely stops them. Reliable protection from alpha particles is also provided by human clothing. Since alpha radiation has the highest ionizing power, but the least penetrating ability, external irradiation with alpha particles is practically harmless, but getting them inside the body is very dangerous.
Beta radiation is a stream of beta particles, which, depending on the energy of the radiation, can propagate at a speed close to the speed of light (300 thousand km/s). Beta particles have less charge and greater speed than alpha particles, so they have less ionizing power but greater penetrating power. The travel distance of high-energy beta particles in air is up to 20 m, in water and living tissues - up to 3 cm, in metal - up to 1 cm. In practice, beta particles almost completely absorb window or car glass and metal screens several millimeters thick. Clothing absorbs up to 50% of beta particles. During external irradiation of the body, 20-25% of beta particles penetrate to a depth of about 1 mm. Therefore, external beta radiation poses a serious danger only when radioactive substances come into direct contact with the skin (especially the eyes) or inside the body.
Gamma radiation is electromagnetic radiation emitted by the nuclei of atoms during radioactive transformations. It usually accompanies beta decay, less often alpha decay. By its nature, gamma radiation is an electromagnetic field with a wavelength of 10~8-10~cm. It is emitted in separate portions (quanta) and propagates at the speed of light. Its ionizing ability is significantly less than that of beta particles and even more so of alpha particles. But gamma radiation has the greatest penetrating ability and can spread hundreds of meters in the air. To weaken its energy by half, a layer of substance (half-attenuation layer) is required with a thickness of: water - 23 cm, steel - about 3, concrete - 10, wood - 30 cm. Due to the greatest penetrating ability, gamma radiation is the most important factor of damaging effect radioactive radiation during external irradiation. Heavy metals, such as lead, which are most often used for these purposes, are good protection against gamma radiation.
100. Effect of radiation on humans
Compared to other damaging factors, ionizing radiation (radiation) has been best studied. How does radiation affect cells? When atomic nuclei fission, large amounts of energy are released, capable of stripping electrons from the atoms of the surrounding substance. This process is called ionization, and the electromagnetic radiation carrying energy is called ionizing. An ionized atom changes its physical and chemical properties. Consequently, the properties of the molecule in which it is included change. The higher the level of radiation, the greater the number of ionization events, the more damaged cells there will be. The body replaces dead cells with new ones within days or weeks, and effectively discards mutant cells. This is what the immune system does. But sometimes protective systems fail. The long-term result may be cancer or genetic changes in descendants, depending on the type of cell damaged (regular or germ cell). Neither outcome is predetermined, but both have some probability. Cancers that occur spontaneously are called spontaneous cases. If an agent is found to be responsible for causing cancer, the cancer is said to be induced.
If the radiation dose exceeds the natural background by hundreds of times, it becomes noticeable to the body. The important thing is not that it is radiation, but that it is more difficult for the body’s defense systems to cope with the increased amount of damage. Due to the increasing frequency of failures, additional “radiation” cancers arise. Their number can be several percent of the number of spontaneous cancers.
Very large doses, this is thousands of times higher than the background. At such doses, the main difficulties of the body are associated not with the changed cells, but with the rapid death of tissues important for the body. The body cannot cope with restoring the normal functioning of the most vulnerable organs, primarily the red bone marrow, which belongs to the hematopoietic system. Signs of acute illness appear - acute radiation sickness. If the radiation does not kill all the bone marrow cells at once, the body will recover over time. Recovery from radiation sickness takes more than one month, but then the person lives a normal life. Having recovered from radiation sickness, people are slightly more likely than their non-irradiated peers to get cancer. By several percent. This follows from observations of patients in different countries of the world who have undergone radiotherapy and those who received fairly large doses of radiation, for employees of the first nuclear enterprises, which did not yet have reliable radiation protection systems, as well as for survivors of the atomic bombing of the Japanese, and Chernobyl liquidators. Among the groups listed, residents of Hiroshima and Nagasaki had the highest doses. Over 60 years of observation, in 86.5 thousand people with doses 100 or more times higher than the natural background, there were 420 more cases of fatal cancer than in the control group (an increase of approximately 10%). Unlike symptoms of acute radiation sickness, which take hours or days to appear, cancer does not appear immediately, perhaps after 5, 10 or 20 years. The latent period is different for different cancer locations. Leukemia (blood cancer) develops most quickly, in the first five years. It is this disease that is considered an indicator of radiation exposure at radiation doses hundreds and thousands of times higher than background.
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Impact result |
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Dose from natural sources per year |
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Maximum permissible dose of occupational exposure per year |
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Doubling rate of gene mutations |
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A single dose of justifiable risk in emergency circumstances |
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Dose of acute radiation sickness |
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Without treatment, 50% of those exposed die within 1-2 months due to disruption of the activity of bone marrow cells |
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Death occurs within 1-2 weeks due to damage mainly to the gastrointestinal tract |
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Death occurs within hours or days due to damage to the central nervous system |