Question 1

In the diagram showing three charged particles moving in a magnetic field (Figure Q24.21), all particles have the same mass and charge magnitude. Which particle is moving the fastest?

Accepted Answer

Particle 3

Question 2

Given the equation for the radius of curvature of a charged particle in a magnetic field $$r = \frac{mv}{qB}$$, what happens to the radius if the velocity of the particle doubles, assuming all other variables remain constant?

Accepted Answer

The radius doubles

Question 3

An electron and a proton are moving in circular orbits in the Earth's magnetic field at the same speed. Which particle takes more time to complete one orbit, and why?

Accepted Answer

The proton, because it has a larger mass

Question 4

A proton moves with a speed of $$1.0 	imes 10^7$ m/s in a 0.50 T magnetic field pointing in the positive x-direction. If the proton's velocity makes a 45° angle with the field, what is the magnitude of the magnetic force on the proton?

Accepted Answer

$$5.7 	imes 10$$^{-13}$$ N

Question 5

If a proton moves parallel to a magnetic field, what is the magnitude of the magnetic force acting on it?

Accepted Answer

$$F = 0$$

Question 6

The aurora is caused by electrons and protons moving in the Earth's magnetic field and colliding with atmospheric molecules. What is the radius of the circular orbit for an electron with speed $$1.0 	imes 10^6$ m/s in a 5.0$$ 	imes $$10^{-5} T $$field?

Accepted Answer

$$1.14 	imes 10$$^{-1}$$ m

Question 7

For a proton with speed $$5.0 	imes 10^4$ m/s in the Earth's magnetic field (5.0$$ 	imes $$10^{-5} T$$), what is the radius of its circular orbit?

Accepted Answer

$$10 m$$

Question 8

What is the frequency of the circular orbit for an electron with speed $$1.0 	imes 10^6$ m/s in a 5.0$$ 	imes $$10^{-5} T $$magnetic field?

Accepted Answer

$$1.4 	imes 10^5$ Hz

Question 9

What is the frequency of the circular orbit for a proton with speed $$5.0 	imes 10^4$ m/s in a 5.0$$ 	imes $$10^{-5} T $$magnetic field?

Accepted Answer

$$760 Hz$$

Question 10

A 2.0 g wire carrying 1.5 A current is placed in a 0.10 m wide region of a magnetic field. What magnetic field strength is required to levitate the wire (balance gravity)?

Accepted Answer

$$0.13 T$$

Question 11

In the wire levitation scenario, what direction must the magnetic field point to produce an upward force on the wire, given the current flows from right to left?

Accepted Answer

Into the page

Question 12

Two parallel wires, each 1.0 m long and 1.0 m apart, carry 1.0 A current. What is the force between them?

Accepted Answer

$$2.0 	imes 10$$^{-7}$$ N

Question 13

The ampere is defined using the force between two parallel wires. If the force per meter is $$2.0 	imes 10$$^{-7}$$ N, what current flows through each wire?

Accepted Answer

1.0 A

Question 14

A 3.0-m-long wire carrying 15 A is placed at a 30° angle to a 2.5 T magnetic field. What is the magnitude of the force on the wire?

Accepted Answer

56 N

Question 15

For the wire in the previous question, what is the direction of the force according to the right-hand rule?

Accepted Answer

Into the page

Question 16

Which equation correctly describes the force on a current-carrying wire in a magnetic field?

Accepted Answer

$$F = ILB \sin \alpha$$

Question 17

If a wire is placed perpendicular to a magnetic field and carries a current, what determines the direction of the force on the wire?

Accepted Answer

The right-hand rule

Question 18

A charged particle moves perpendicular to a uniform magnetic field. What type of motion does it undergo?

Accepted Answer

Uniform circular motion

Question 19

Which of the following best explains why the aurora is visible at the poles?

Accepted Answer

Charged particles spiral along magnetic field lines and collide with atmospheric molecules, causing them to glow

Question 20

If the mass of a charged particle increases while all other variables remain constant, what happens to the period of its circular orbit in a magnetic field?

Accepted Answer

The period increases

Magnetic Force on Moving Charges and Currents – Step-by-Step Study Guidance

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