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11TH GRADE PRACTICE

Physics Problems: Magnetism, Grade 11

Magnetic field forces and induction.

11 problems2 subtopics
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CONDITIONS

Problems

11
№ 1

Problem 1

Magnetism: magnetic field forces

A conductor with a current of 5 A5\,\text{A} and a length of 40 cm40\,\text{cm} in a magnetic field is subject to a maximum force of 5 mN5\,\text{mN}. What is the magnetic field induction?

  1. 0,005 Tl0{,}005\,\text{Tl}
  2. 0,025 Tl0{,}025\,\text{Tl}
  3. 0,0025 Tl0{,}0025\,\text{Tl}
  4. 0,00125 Tl0{,}00125\,\text{Tl}
№ 2

Problem 2

Magnetism: magnetic field forces

What should be the angle between a conductor of length 20 cm20\,\text{cm} and the magnetic induction vector B=4 mTB=4\,\text{mT}, so that at a current of 15 A15\,\text{A} the force is: a) 6 mN6\,\text{mN}, b) 18 mN18\,\text{mN}?

  1. (60∘; 30∘)\left(60^{\circ};\ 30^{\circ}\right)
  2. (45∘; 90∘)\left(45^{\circ};\ 90^{\circ}\right)
  3. (30∘; 60∘)\left(30^{\circ};\ 60^{\circ}\right)
  4. (30∘; vtoroy sluchay nevozmozhen)\left(30^{\circ};\ \text{vtoroy sluchay nevozmozhen}\right)
№ 3

Problem 3

Magnetism: magnetic field forces

The electron moves at a speed of 2⋅107 m/s2\cdot10^{7}\,\text{m/s} perpendicular to the field with an induction of 40 mT40\,\text{mT}. Determine the Lorentz force, the radius of the trajectory and the period of revolution.

  1. (1,28⋅10−13 N; 0,0028 m; 8,9⋅10−10 s)\left(1{,}28 \cdot 10^{-13}\,\text{N};\ 0{,}0028\,\text{m};\ 8{,}9 \cdot 10^{-10}\,\text{s}\right)
  2. (6,4⋅10−14 N; 0,0014 m; 4,45⋅10−10 s)\left(6{,}4 \cdot 10^{-14}\,\text{N};\ 0{,}0014\,\text{m};\ 4{,}45 \cdot 10^{-10}\,\text{s}\right)
  3. (2,56⋅10−13 N; 0,0056 m; 1,78⋅10−9 s)\left(2{,}56 \cdot 10^{-13}\,\text{N};\ 0{,}0056\,\text{m};\ 1{,}78 \cdot 10^{-9}\,\text{s}\right)
  4. (1,28⋅10−12 N; 0,028 m; 8,9⋅10−9 s)\left(1{,}28 \cdot 10^{-12}\,\text{N};\ 0{,}028\,\text{m};\ 8{,}9 \cdot 10^{-9}\,\text{s}\right)
№ 4

Problem 4

Magnetism: magnetic field forces

Homogeneous electric and magnetic fields are mutually perpendicular: E=0,5 kV/mE=0{,}5\,\text{kV/m}, B=0,001 TB=0{,}001\,\text{T}. At what speed and in what direction should the electron move uniformly?

  1. 5⋅105 m/s vdol elekfricheskogo usefulya5\cdot10^{5}\,\text{m/s}\ \text{vdol elekfricheskogo usefulya}
  2. 5⋅105 m/s perpendikulyarno oboim usefulyam5\cdot10^{5}\,\text{m/s}\ \text{perpendikulyarno oboim usefulyam}
  3. 5⋅102 m/s vdol elekfricheskogo usefulya5\cdot10^{2}\,\text{m/s}\ \text{vdol elekfricheskogo usefulya}
  4. 2⋅106 m/s vdol magnitnogo usefulya2\cdot10^{6}\,\text{m/s}\ \text{vdol magnitnogo usefulya}
№ 5

Problem 5

Magnetism: magnetic field forces

The proton flew into the magnetic field at a speed of 500 km/s500\,\text{km/s} perpendicular to the induction vector. Determine the orbital radius and orbital period at B=30 mTB=30\,\text{mT}.

  1. (0,348 m; 4,4⋅10−6 s)\left(0{,}348\,\text{m};\ 4{,}4 \cdot 10^{-6}\,\text{s}\right)
  2. (1,74 m; 2,2⋅10−5 s)\left(1{,}74\,\text{m};\ 2{,}2 \cdot 10^{-5}\,\text{s}\right)
  3. (0,174 m; 2,2⋅10−6 s)\left(0{,}174\,\text{m};\ 2{,}2 \cdot 10^{-6}\,\text{s}\right)
  4. (0,087 m; 1,1⋅10−6 s)\left(0{,}087\,\text{m};\ 1{,}1 \cdot 10^{-6}\,\text{s}\right)
№ 6

Problem 6

Magnetism: magnetic field forces

In a magnetic field with an induction of 4 mT4\,\text{mT}, a horizontal conductor with a length of 20 cm20\,\text{cm} and a mass of 16 g16\,\text{g} is in equilibrium. The conductor is perpendicular to the induction vector. Determine the current.

  1. 100 A100\,\text{A}
  2. 400 A400\,\text{A}
  3. 2000 A2000\,\text{A}
  4. 200 A200\,\text{A}
№ 7

Problem 7

Magnetism: electromagnetic induction

A coil with a diameter of 5 cm5\,\text{cm} has 200200 turns and is located in a magnetic field parallel to the axis of the coil. What is the EMF if in 0,3 s0{,}3\,\text{s} the induction changed from 80 mT80\,\text{mT} to 20 mT20\,\text{mT}?

  1. 0,08 V0{,}08\,\text{V}
  2. 0,04 V0{,}04\,\text{V}
  3. 0,16 V0{,}16\,\text{V}
  4. 0,8 V0{,}8\,\text{V}
№ 8

Problem 8

Magnetism: electromagnetic induction

When the current in a coil with inductance 0,2 H0{,}2\,\text{H} changed for 0,1 s0{,}1\,\text{s}, a self-inductive emf 3 V3\,\text{V} arose. How much has the current changed?

  1. 15 A15\,\text{A}
  2. 1,5 A1{,}5\,\text{A}
  3. 0,75 A0{,}75\,\text{A}
  4. 3 A3\,\text{A}
№ 9

Problem 9

Magnetism: electromagnetic induction

A current of 8 A8\,\text{A} flows in a coil with inductance 0,5 H0{,}5\,\text{H}. What is the energy of the magnetic field? How to change the current so that the energy increases 99 times?

  1. (32 Dzh; 48 A)\left(32\,\text{Dzh};\ 48\,\text{A}\right)
  2. (160 Dzh; 240 A)\left(160\,\text{Dzh};\ 240\,\text{A}\right)
  3. (16 Dzh; 24 A)\left(16\,\text{Dzh};\ 24\,\text{A}\right)
  4. (8 Dzh; 12 A)\left(8\,\text{Dzh};\ 12\,\text{A}\right)
№ 10

Problem 10

Magnetism: electromagnetic induction

A closed conductor with a resistance of 3 Ohm3\,\text{Ohm} is in a magnetic field. What charge will pass through the conductor when the magnetic flux changes by 3⋅10−4 Wb3\cdot10^{-4}\,\text{Wb}?

  1. 5⋅10−5 Kl5 \cdot 10^{-5}\,\text{Kl}
  2. 2⋅10−4 Kl2 \cdot 10^{-4}\,\text{Kl}
  3. 0,001 Kl0{,}001\,\text{Kl}
  4. 1⋅10−4 Kl1 \cdot 10^{-4}\,\text{Kl}
№ 11

Problem 11

Magnetism: magnetic field forces

An electron flies perpendicularly into a magnetic field with a speed of 5 Mm/s5\,\text{Mm/s} and moves in a circle of radius 1,1 cm1{,}1\,\text{cm}. Determine the field induction and revolution period.

  1. (0,0026 Tl; 1,38⋅10−8 s)\left(0{,}0026\,\text{Tl};\ 1{,}38 \cdot 10^{-8}\,\text{s}\right)
  2. (0,0013 Tl; 6,9⋅10−9 s)\left(0{,}0013\,\text{Tl};\ 6{,}9 \cdot 10^{-9}\,\text{s}\right)
  3. (0,0052 Tl; 2,76⋅10−8 s)\left(0{,}0052\,\text{Tl};\ 2{,}76 \cdot 10^{-8}\,\text{s}\right)
  4. (0,026 Tl; 1,38⋅10−7 s)\left(0{,}026\,\text{Tl};\ 1{,}38 \cdot 10^{-7}\,\text{s}\right)

THEORY

Lessons on the topic

Magnetic field and forcesInduction, Ampere force, Lorentz force and charge motion.Magnetic flux and inductionFlux, electromagnetic induction, self-induction and field energy.

DIRECTORY

Formulas by topic

InductanceL · GnMagnetic inductionB · TlMagnetic fluxΦ · WbSpeedv · m/sEnergyE, W · J