Solution. The mass can be calculated using the formula. A force that is twice as strong imparts 4 times the acceleration to a body with mass .
Correct answer: 2.
A3. At what stage of flight in a spacecraft that becomes an Earth satellite in orbit will weightlessness be observed?
Solution. Weightlessness is observed in the absence of all external forces, with the exception of gravitational forces. These are the conditions in which a spacecraft finds itself during an orbital flight with the engine turned off.
Correct answer: 3.
A4. Two balls with masses m and 2 m move with speeds equal to 2, respectively v And v. The first ball moves after the second and, having caught up, sticks to it. What is the total momentum of the balls after impact?
| 1) | mv |
| 2) | 2mv |
| 3) | 3mv |
| 4) | 4mv |
Solution. According to the law of conservation, the total momentum of the balls after the collision is equal to the sum of the impulses of the balls before the collision: .
Correct answer: 4.
A5. Four identical sheets of plywood thickness L Each one, tied in a stack, floats in the water so that the water level corresponds to the boundary between the two middle sheets. If you add another sheet of the same type to the stack, the immersion depth of the stack of sheets will increase by
| 1) | |
| 2) | |
| 3) | |
| 4) |
Solution. The immersion depth is half the height of the stack: for four sheets - 2 L, for five sheets - 2.5 L. The immersion depth will increase by .
Correct answer: 3.
A6. The figure shows a graph of the change over time in the kinetic energy of a child swinging on a swing. At the moment corresponding to the point A on the graph, its potential energy, measured from the equilibrium position of the swing, is equal to
| 1) | 40 J |
| 2) | 80 J |
| 3) | 120 J |
| 4) | 160 J |
Solution. It is known that in the equilibrium position a maximum of kinetic energy is observed, and the difference in potential energies in two states is equal in magnitude to the difference in kinetic energies. The graph shows that the maximum kinetic energy is 160 J, and for the point A it is equal to 120 J. Thus, the potential energy measured from the equilibrium position of the swing is equal to .
Correct answer: 1.
A7. Two material points move in circles with radii and equal velocities. Their periods of revolution in circles are related by the relation
| 1) | |
| 2) | |
| 3) | |
| 4) |
Solution. The period of revolution around a circle is equal to . Because , then .
Correct answer: 4.
A8. In liquids, particles oscillate near an equilibrium position, colliding with neighboring particles. From time to time the particle makes a “jump” to another equilibrium position. What property of liquids can be explained by this nature of particle motion?
Solution. This nature of the movement of liquid particles explains its fluidity.
Correct answer: 2.
A9. Ice at a temperature of 0 °C was brought into a warm room. Temperature of ice before it melts
Solution. The temperature of the ice before it melts will not change, since all the energy received by the ice at this time is spent on destroying the crystal lattice.
Correct answer: 1.
A10. At what air humidity does a person tolerate high air temperatures more easily and why?
Solution. A person can more easily tolerate high air temperatures with low humidity, since sweat evaporates quickly.
Correct answer: 1.
A11. The absolute body temperature is 300 K. On the Celsius scale it is equal to
Solution. On the Celsius scale it is equal to .
Correct answer: 2.
A12. The figure shows a graph of the volume of an ideal monatomic gas versus pressure in process 1–2. The internal energy of the gas increased by 300 kJ. The amount of heat imparted to the gas in this process is equal to
Solution. The efficiency of a heat engine, the useful work it performs and the amount of heat received from the heater are related by the equality , whence .
Correct answer: 2.
A14. Two identical light balls, the charges of which are equal in magnitude, are suspended on silk threads. The charge of one of the balls is indicated in the figures. Which of the pictures corresponds to the situation when the charge of the 2nd ball is negative?
| 1) | A |
| 2) | B |
| 3) | C And D |
| 4) | A And C |
Solution. The indicated charge of the ball is negative. Like charges repel each other. The repulsion is observed in the figure A.
Correct answer: 1.
A15. An α particle moves in a uniform electrostatic field from a point A to the point B along trajectories I, II, III (see figure). Work of electrostatic field forces
Solution. The electrostatic field is potential. In it, the work of moving the charge does not depend on the trajectory, but depends on the position of the starting and ending points. For the drawn trajectories, the starting and ending points coincide, which means that the work of the electrostatic field forces is the same.
Correct answer: 4.
A16. The figure shows a graph of the current in a conductor versus the voltage at its ends. What is the resistance of the conductor?
Solution. In an aqueous salt solution, current is created only by ions.
Correct answer: 1.
A18. An electron flying into the gap between the poles of an electromagnet has a horizontally directed speed perpendicular to the magnetic field induction vector (see figure). Where is the Lorentz force acting on the electron directed?
Solution. Let’s use the “left hand” rule: point four fingers in the direction of the electron’s movement (away from ourselves), and turn the palm so that the magnetic field lines enter it (to the left). Then the protruding thumb will show the direction of the acting force (it will be directed downward) if the particle were positively charged. The electron charge is negative, which means the Lorentz force will be directed in the opposite direction: vertically upward.
Correct answer: 2.
A19. The figure shows a demonstration of an experiment to verify Lenz's rule. The experiment is carried out with a solid ring, not a cut one, because
Solution. The experiment is carried out with a solid ring, because an induced current arises in a solid ring, but not in a cut one.
Correct answer: 3.
A20. The decomposition of white light into a spectrum when passing through a prism is due to:
Solution. Using the formula for the lens, we determine the position of the image of the object:
If you place the film plane at this distance, you will get a clear image. It can be seen that 50 mm
Correct answer: 3.
A22. Speed of light in all inertial frames of reference
Solution. According to the postulate of the special theory of relativity, the speed of light in all inertial frames of reference is the same and does not depend either on the speed of the light receiver or on the speed of the light source.
Correct answer: 1.
A23. Beta radiation is
Solution. Beta radiation is a stream of electrons.
Correct answer: 3.
A24. The thermonuclear fusion reaction releases energy, and:
A. The sum of the charges of the particles - the reaction products - is exactly equal to the sum of the charges of the original nuclei.
B. The sum of the masses of the particles - the reaction products - is exactly equal to the sum of the masses of the original nuclei.
Are the above statements true?
Solution. The charge is always maintained. Since the reaction occurs with the release of energy, the total mass of the reaction products is less than the total mass of the original nuclei. Only A is correct.
Correct answer: 1.
A25. A load weighing 10 kg is applied to a moving vertical wall. The coefficient of friction between the load and the wall is 0.4. With what minimum acceleration must the wall be moved to the left so that the load does not slide down?
| 1) | |
| 2) | |
| 3) | |
| 4) |
Solution. To prevent the load from sliding down, it is necessary that the friction force between the load and the wall balances the force of gravity: . For a load that is motionless relative to the wall, the relation is true, where μ is the friction coefficient, N- the support reaction force, which, according to Newton’s second law, is related to the acceleration of the wall by the equality . As a result we get:
Correct answer: 3.
A26. A plasticine ball weighing 0.1 kg flies horizontally at a speed of 1 m/s (see figure). It hits a stationary cart of mass 0.1 kg attached to a light spring and sticks to the cart. What is the maximum kinetic energy of the system during its further oscillations? Ignore friction. The blow is considered instantaneous.
| 1) | 0.1 J |
| 2) | 0.5 J |
| 3) | 0.05 J |
| 4) | 0.025 J |
Solution. According to the law of conservation of momentum, the speed of a cart with a stuck plasticine ball is equal to
Correct answer: 4.
A27. Experimenters pump air into a glass vessel, simultaneously cooling it. At the same time, the air temperature in the vessel decreased by 2 times, and its pressure increased by 3 times. How many times has the mass of air in the container increased?
| 1) | 2 times |
| 2) | 3 times |
| 3) | 6 times |
| 4) | 1.5 times |
Solution. Using the Mendeleev-Clapeyron equation, you can calculate the mass of air in the vessel:
.
If the temperature dropped by 2 times and its pressure increased by 3 times, then the mass of air increased by 6 times.
Correct answer: 3.
A28. A rheostat is connected to a current source with an internal resistance of 0.5 Ohm. The figure shows a graph of the current in the rheostat versus its resistance. What is the emf of the current source?
| 1) | 12 V |
| 2) | 6 V |
| 3) | 4 V |
| 4) | 2 V |
Solution. According to Ohm's law for a complete circuit:
.
When the external resistance is equal to zero, the emf of the current source is found by the formula:
Correct answer: 2.
A29. A capacitor, inductor and resistor are connected in series. If, with a constant frequency and voltage amplitude at the ends of the circuit, the capacitance of the capacitor is increased from 0 to , then the amplitude of the current in the circuit will be
Solution. The AC resistance of the circuit is 
. The current amplitude in the circuit is equal to
.
This dependency as a function WITH on the interval has a maximum at . The amplitude of the current in the circuit will first increase and then decrease.
Correct answer: 3.
A30. How many α- and β-decays must occur during the radioactive decay of a uranium nucleus and its eventual transformation into a lead nucleus?
| 1) | 10 α and 10 β decays |
| 2) | 10 α and 8 β decays |
| 3) | 8 α and 10 β decays |
| 4) | 10 α and 9 β decays |
Solution. During α decay, the mass of the nucleus decreases by 4 a. e.m., and during β-decay the mass does not change. In a series of decays, the mass of the nucleus decreased by 238 – 198 = 40 a. e.m. For such a decrease in mass, 10 α decays are required. With α-decay, the charge of the nucleus decreases by 2, and with β-decay, it increases by 1. In a series of decays, the charge of the nucleus decreased by 10. For such a decrease in charge, in addition to 10 α-decays, 10 β-decays are required.
Correct answer: 1.
Part B
B1. A small stone thrown from a flat horizontal surface of the earth at an angle to the horizon fell back to the ground after 2 s, 20 m from the point of throw. What is the minimum speed of the stone during flight?
Solution. In 2 s, the stone covered 20 m horizontally; therefore, the component of its velocity directed along the horizon is 10 m/s. The speed of the stone is minimal at the highest point of flight. At the top point, the total speed coincides with its horizontal projection and, therefore, is equal to 10 m/s.
B2. To determine the specific heat of melting of ice, pieces of melting ice were thrown into a vessel with water with continuous stirring. Initially, the vessel contained 300 g of water at a temperature of 20 °C. By the time the ice stopped melting, the mass of water had increased by 84 g. Based on the experimental data, determine the specific heat of melting of ice. Express your answer in kJ/kg. Neglect the heat capacity of the vessel.
Solution. The water gave off heat. This amount of heat was used to melt 84 g of ice. The specific heat of melting of ice is 
.
Answer: 300.
B3. When treating with an electrostatic shower, a potential difference is applied to the electrodes. What charge passes between the electrodes during the procedure, if it is known that the electric field does work equal to 1800 J? Express your answer in mC.
Solution. The work done by the electric field to move a charge is equal to . Where can we express the charge:
.
Q4. A diffraction grating with a period is located parallel to the screen at a distance of 1.8 m from it. What order of magnitude maximum in the spectrum will be observed on the screen at a distance of 21 cm from the center of the diffraction pattern when the grating is illuminated by a normally incident parallel beam of light with a wavelength of 580 nm? Count .
Solution. The deflection angle is related to the lattice constant and the wavelength of light by the equality . The deviation on the screen is . Thus, the order of the maximum in the spectrum is equal to
Part C
C1. The mass of Mars is 0.1 of the mass of the Earth, the diameter of Mars is half that of the Earth. What is the ratio of the orbital periods of artificial satellites of Mars and Earth moving in circular orbits at low altitude?
Solution. The orbital period of an artificial satellite moving around the planet in a circular orbit at low altitude is equal to
Where D- diameter of the planet, v- the speed of the satellite, which is related to the centripetal acceleration ratio.
364. The figure shows a coil of wire through which electric current flows in the direction indicated by the arrow. The coil is located in the plane of the drawing. At the center of the coil, the magnetic field induction vector of the current is directed
365. Two thin straight conductors parallel to each other carry the same currents I(see picture). What is the direction of the magnetic field they create at point C?
366. What needs to be done to change the poles of the magnetic field of a current-carrying coil?
1) reduce the current 2) change the direction of the current in the coil
3) turn off the current source 4) increase the current strength
367.
368.
A permanent strip magnet was brought to the magnetic needle (the north pole is darkened, see figure), which can rotate around a vertical axis perpendicular to the plane of the drawing. In this case the arrow
369. What is the force with which a uniform magnetic field with an induction of 2.5 Tesla acts on a conductor 50 cm long, located at an angle of 30° to the induction vector, with a current strength in the conductor of 0.5 A:
1) 31.25 N; 2) 54.38 N; 3) 0.55 N; 4) 0.3125 N?
371. An electrical circuit consisting of four straight horizontal conductors (1 – 2, 2 – 3, 3 – 4, 4 – 1) and a direct current source is in a uniform magnetic field, the magnetic induction vector of which is directed horizontally to the right (see figure, view above). Where is the Ampere force caused by this field directed, acting on conductor 1 - 2?
372.
What is the direction of the Ampere force acting on conductor No. 1 from the side of the other two (see figure), if all the conductors are thin, lie in the same plane, parallel to each other and the distances between adjacent conductors are the same? (I – current strength.)
373. A section of conductor 10 cm long is in a magnetic field with an induction of 50 mT. Ampere's force, when moving a conductor 8 cm in the direction of its action, does 0.004 J of work. What is the strength of the current flowing through the conductor? The conductor is located perpendicular to the lines of magnetic induction.
375. Electron e and proton p fly into a uniform magnetic field perpendicular to the magnetic induction vector with speeds 2v and v, respectively. The ratio of the modulus of the force acting on the electron from the magnetic field to the modulus of the force acting on the proton at this moment in time is equal to
377.
An electron e – flying into the gap between the poles of an electromagnet has a horizontal speed perpendicular to the magnetic field induction vector (see figure). Where is the Lorentz force acting on it directed?
378.
An electron e – that has flown into the gap between the poles of an electromagnet has a horizontally directed speed perpendicular to the magnetic field induction vector (see figure). Where is the Lorentz force acting on it directed?
379. Na+ ion mass m flies into a magnetic field with a speed perpendicular to the lines of induction of the magnetic field and moves along an arc of a circle of radius R. The magnitude of the magnetic field induction vector can be calculated using the expression
| 1) | 2) | 3) | 4) |
380. Two initially stationary electrons are accelerated in an electric field: the first in a field with a potential difference U, the second - 2U. The accelerated electrons enter a uniform magnetic field, the induction lines of which are perpendicular to the speed of the electrons. The ratio of the radii of curvature of the trajectories of the first and second electrons in a magnetic field is equal to
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Test on the topic Electromagnetism for 11th grade students with answers. The test consists of 5 options, each with 8 tasks.
1 option
A1. A permanent magnet was brought to the magnetic needle (the north pole is darkened, see figure), which can rotate around a vertical axis perpendicular to the plane of the drawing. In this case the arrow
1) rotate 180°
2) rotate 90° clockwise
3) rotate 90° counterclockwise
A2. A section of conductor 10 cm long is in a magnetic field. The strength of the electric current flowing through the conductor is 10 A. When the conductor moves 8 cm in the direction of the Ampere force, it does 0.004 J of work. What is the magnetic field induction? The conductor is located perpendicular to the lines of magnetic induction.
1) 0.0005 T
2) 0.005 T
3) 0.032 T
4) 0.05 T
A3. Proton r flying into the gap between the poles of an electromagnet has a horizontal speed v IN magnetic field directed downwards (see figure). Where is the Lorentz force acting on a proton directed? F?
1) Vertically down
2) Vertically up
3) Horizontally towards us
4) Horizontally from us
A4. In 5 s, the magnetic flux penetrating the wire frame increased from 3 to 8 Wb. What is the value of the induced emf in the frame?
1) 0.6 V
2) 1 V
3) 1.6 V
4) 25 V
A5.
The self-induction EMF module takes equal values in time intervals
1) 0-1 s and 1-3 s
2) 3-4 s and 4-7 s
3) 1-3 s and 4-7 s
4) 0-1 s and 3-4 s
B1. Horizontal rails are spaced 30 cm apart. A rod weighing 100 g rests on them perpendicular to the rails. The entire system is located in a vertical magnetic field with an induction of 0.5 Tesla. When a current of 2 A is passed through the rod, it moves with an acceleration of 2 m/s 2 Find the coefficient of friction between the rails and the rod.
B2. Particle with mass m, carrying charge q IN circumferential radius R at speed v. What will happen to the orbital radius, orbital period and kinetic energy of the particle as the magnetic field induction increases?
Physical quantities
A) orbital radius
B) circulation period
B) kinetic energy
Their change
1) will increase
2) will decrease
3) will not change
C1. A coil of wire having an area of 10 cm 2 is cut at a certain point, and a 10 μF capacitor is included in the cut. The coil is placed in a uniform magnetic field, the lines of force of which are perpendicular to the plane of the coil. The magnetic field induction uniformly decreases over 0.2 s by 0.01 Tesla. Determine the charge on the capacitor.
Option 2
A1. A conductor located in a uniform magnetic field at an angle of 30° to the direction of the magnetic induction lines is acted upon by a force F. If this angle is increased by 3 times, then a force equal to
1) 0
2) F/2
3) 2F
4) 3F
A2. A section of conductor 20 cm long is in a magnetic field with an induction of 25 mT. Ampere's force, when moving a conductor 8 cm in the direction of its action, does 0.004 J of work. The conductor is located perpendicular to the lines of magnetic induction. What is the strength of the current flowing through the conductor?
1) 0.01 A
2) 0.1 A
3) 10 A
4) 64 A
A3. Proton r flying into the gap between the poles of an electromagnet has a horizontal speed v, perpendicular to the induction vector IN magnetic field directed upward (see figure). Where is the Lorentz force acting on a proton directed? F?
1) Vertically down
2) Vertically up
3) Horizontally towards us
4) Horizontally from us
A4. A wire frame with an area S = 2 m 2 is located perpendicular to the lines of the magnetic induction vector of a uniform magnetic field. The magnitude of the magnetic induction vector is 0.04 Tesla. Over time t = 0.01 s, the magnetic field uniformly decreases to zero. What is the induced emf generated in the frame?
1) 8 V
2) 2 V
3) 0.8 mV
4) 0 V
A5. The figure shows a graph of the change in current strength in the inductor over time.
The module of the self-induction EMF takes the greatest value in the period of time
1) 0-1 s
2) 1-5 s
3) 5-6 s
4) 6-8 s
B1. At what speed does an alpha particle fly out of a radioactive nucleus if it enters a uniform magnetic field by induction IN= 2 Tesla perpendicular to its field lines, moves along a circular arc with radius R= 1 m? (The mass of the α-particle is 6.7 · 10 -27 kg, its charge is 3.2 · 10 -19 C).
B2. Particle with mass m, carrying charge q, moves in a uniform magnetic field with induction IN circumferential radius R at speed v. What happens to the orbital radius, orbital period and kinetic energy of the particle when the magnetic field induction decreases?
For each position in the first column, select the corresponding position in the second.
Physical quantities
A) orbital radius
B) circulation period
B) kinetic energy
Their changes
1) will increase
2) will decrease
3) will not change
C1. Particle with charge q and mass m flies into a region of uniform magnetic field with induction IN. Particle speed v directed perpendicular to the field lines and the boundary of the region. After passing through the field region, the particle flies out at an angle α to the initial direction of motion. At what distance l from the entry point into the field, a particle will fly out of the area, busy field?
Option 3
A1. A permanent magnet was brought to the magnetic needle (the north pole is darkened, see figure), which can rotate around a vertical axis perpendicular to the plane of the drawing. In this case the arrow
1) rotate 180°
4) will remain in the same position
A2. The conductor section is in a magnetic field, the induction of which is 40 mT. The strength of the electric current flowing through the conductor is 12.5 A. When the conductor moves 8 cm in the direction of the Ampere force, the field does 0.004 J of work. The conductor is located perpendicular to the lines of magnetic induction. What is the length of the conductor section?
1) 10 m
2) 0.1 m
3) 0.064 m
4) 0.001 m
A3. v IN F?
1) Vertically down
2) Vertically up
3) Horizontal left
4) Horizontal right
A4. In an experiment to study the EMF of electromagnetic induction, a square frame made of thin wire with a square side b is in a uniform magnetic field perpendicular to the plane of the frame. The field induction increases over time t according to a linear law from 0 to the maximum value B max. How will the induced emf in the frame change if b is doubled?
1) Will not change
2) Will increase 2 times
3) Will decrease by 2 times
4) Will increase 4 times
A5. The figure shows a graph of current versus time in an electrical circuit whose inductance is 1 mH. Determine the module of the average value of the self-induction emf in the time interval from 10 to 15 s.
1) 2 µV
2) 3 µV
3) 5 µV
4) 0
B1. A straight conductor 20 cm long and weighing 50 g is suspended on two light threads in a uniform magnetic field, the induction vector of which is directed horizontally and perpendicular to the conductor. How much current must be passed through the conductor for one of the threads to break? Field induction 50 mT. Each thread breaks at a load of 0.4 N.
B2. Particle with mass m, carrying charge q, moves in a uniform magnetic field with induction IN circumferential radius R at speed v. What will happen to the orbital radius, orbital period and momentum of the particle as the magnetic field induction increases?
For each position in the first column, select the corresponding position in the second.
Physical quantities
A) orbital radius
B) circulation period
B) particle momentum
Their changes
1) will increase
2) will decrease
3) will not change
C1. A square is made from a 2 m long wire, which is located horizontally. What electric charge will flow through the wire if it is pulled by two diagonally opposite vertices so that it forms a line? Wire resistance 0.1 Ohm. The vertical component of the Earth's magnetic field is 50 µT.
Option 4
A1. Straight conductor length l with current I placed in a uniform magnetic field, the direction of the induction lines of which is opposite to the direction of the current. If the current strength is reduced by 2 times, and the magnetic field induction is increased by 4 times, then the Ampere force acting on the conductor
1) will increase 2 times
2) will not change
3) will decrease by 4 times
4) will decrease by 2 times
A2. A section of conductor 10 cm long is in a magnetic field with an induction of 50 mT. The strength of the electric current flowing through the conductor is 5 A. The conductor is located perpendicular to the lines of magnetic induction. How much work does the Ampere force do when moving a conductor 80 cm in the direction of its action?
1) 0.004 J
2) 0.4 J
3) 0.5 J
4) 0.625 J
A3. An electron e - flying into the gap between the poles of an electromagnet has a horizontal speed v, perpendicular to the induction vector IN magnetic field (see figure). Where is the Lorentz force acting on it directed? F?
1) To us because of the plane of the drawing
2) From us perpendicular to the drawing plane
3) Horizontally to the left in the drawing plane
4) Horizontally to the right in the drawing plane
A4. E 1. When the speed of movement of the conductor decreases by 2 times, the induced emf E 2 will be equal
1) 2E 1
2) E 1
3) 0,5E 1
4) 0,25E 1
A5. Two coils are placed on an iron core. An ammeter is connected to the first one, the current in the second one changes according to the given graph. At what time intervals will the ammeter show the presence of current in the first coil?
1) 0-1 s and 2-4 s
2) 0-1 s and 4-7 s
3) 1-2 s and 4-7 s
4) 1-2 s and 3-4 s
B1. An electron with a charge e= 1.6 10 -19 C, moves in a uniform magnetic field by induction IN in a circular orbit with radius R= 6 10 -4 m. The value of the particle momentum is r= 4.8 10 -24 kg m/s. What is induction equal to? IN magnetic field?
B2. Particle with mass m, carrying charge q IN circumferential radius R at speed v. What happens to the orbital radius, orbital period and momentum of the particle when the magnetic field induction decreases?
For each position in the first column, select the corresponding position in the second.
Physical quantities
A) orbital radius
B) circulation period
B) particle momentum
Their changes
1) will increase
2) will decrease
3) will not change
C1. Alpha particles with a mass of m and charge q and move in a uniform magnetic field with induction IN, the lines of force of which are perpendicular to the plane of the drawing. At a distance L from the source there is a target of radius r. At what speeds will the α-particles hit the target surface?
Option 5
A1. A permanent magnet was brought to the magnetic needle (the north pole is darkened, see figure), which can rotate around a vertical axis perpendicular to the plane of the drawing. In this case the arrow
1) rotate 180°
2) rotate 90° clockwise
3) rotate 90° counterclockwise
4) will remain in the same position
A2. A section of conductor 5 cm long is in a magnetic field with an induction of 50 mT. The strength of the electric current flowing through the conductor is 20 A. The conductor is located perpendicular to the lines of magnetic induction. What displacement does the conductor make in the direction of the Ampere force if the work done by this force is 0.004 J?
1) 0.0008 m
2) 0.08 m
3) 0.8 m
4) 8 m
A3. An electron e - flying into the gap between the poles of an electromagnet has a horizontally directed speed v, perpendicular to the magnetic field induction vector IN(see picture). Where is the Lorentz force acting on an electron directed? F?
1) Vertically down
2) Vertically up
3) Horizontal left
4) Horizontal right
A4. When a conductor moves in a uniform magnetic field, an induced emf occurs in the conductor E 1 When the speed of movement of the conductor increases by 2 times, the induced emf E 2 will be equal
1) 2E 1
2) E 1
3) 0,5E 1
4) 0,25E 1
A5. The figure shows the change in current strength in the inductor over time.
The module of self-induction EMF takes the greatest value in intervals of time
1) 0-1 s and 2-3 s
2) 1-2 and 2-3 s
3) 0-1 s and 3-4 s
4) 2-3 s and 3-4 s
B1. Horizontal rails are 40 cm apart. The rod rests on them perpendicular to the rails. What should be the magnetic field induction IN so that the rod begins to move if a current of 50 A is passed through it? The coefficient of friction on the rod rails is 0.2. Rod weight 500 g.
B2. Particle with mass m, carrying charge q, moves in a uniform magnetic field by induction IN circumferential radius R at speed v. What happens to the orbital radius, orbital period, and momentum of the particle as the particle's charge decreases?
For each position in the first column, select the corresponding position in the second.
Physical quantities
A) orbital radius
B) circulation period
B) particle momentum
Their changes
1) will increase
2) will decrease
3) will not change
C1. A positively charged particle enters a uniform magnetic field. The speed of the particle is perpendicular to the direction of the magnetic field induction vector. The field area has a width l. At what minimum speed will the particle overcome the region occupied by the magnetic field?
Answers to a test on the topic Electromagnetism, grade 11
1 option
A1-1
A2-4
A3-4
A4-2
A5-4
B1-0.1
B2-223
C1. 5 10 -10 C
Option 2
A1-3
A2-3
A3-3
A4-1
A5-3
B1. 9.55 10 7 m/s
B2-113
C1. l=((mv)/(qB))(1-cosα)
Option 3
A1-2
A2-2
A3-2
A4-4
A5-4
B1. 30 A
B2-221
C1. 125 µC
Option 4
A1-2
A2-1
A3-2
A4-3
A5-3
B1. 0.05 T
B2-112
C1. v≤(qB(r 2 +L 2))/(2rm)
Option 5
A1-4
A2-2
A3-1
A4-1
A5-3
B1. 0.05 T
B2-112
C1. v>(lqB)/m
