Question 1

Which of the following statements best describes the direction of the magnetic field at a point in space?

Accepted Answer

It is the direction indicated by the north pole of a small compass needle placed at that point.

Question 2

A charged particle moves with velocity $$\vec{v}$$ perpendicular to a uniform magnetic field $$\vec{B}. $$What is the magnitude of the magnetic force acting on the particle?

Accepted Answer

$$F = qvB$$

Question 3

Which of the following is NOT a valid method for generating a magnetic field?

Accepted Answer

Placing a stationary charge in an electric field

Question 4

A proton with mass $$m$$ and charge $$q$$ enters a region with a uniform magnetic field $$B at $$velocity $$v$$ perpendicular to $$B. $$What is the radius of its circular path?

Accepted Answer

$$r = \frac{mv}{qB}$$

Question 5

The SI unit of the magnetic field $$B is$$:

Accepted Answer

Tesla (T)

Question 6

A wire of length $$L$$ carries a current $$I in a $$uniform magnetic field $$B. $$The angle between the wire and the field is $$	heta. $$What is the magnitude of the force on the wire?

Accepted Answer

$$F = ILB \sin 	heta$$

Question 7

A rectangular coil with $$N$$ turns, area $$A$$, and current $$I is $$placed in a uniform magnetic field $$B. $$The angle between the normal to the coil and the field is $$\phi. $$What is the torque on the coil?

Accepted Answer

$$	au = NIAB \sin \phi$$

Question 8

Which of the following best describes the path of a charged particle entering a uniform magnetic field at an angle other than $$0^\circ or$$ $$90^\circ to $$the field?

Accepted Answer

It follows a helical path.

Question 9

In a mass spectrometer, ions of the same charge but different masses are separated based on their:

Accepted Answer

Radius of curvature in a magnetic field

Question 10

The pitch $$p of $$the helical path of a charged particle in a uniform magnetic field is given by:

Accepted Answer

$$p = T v_\parallel = \frac{2 \pi m v \cos \phi}{|q| B}$$

Question 11

Which of the following statements about magnetic field lines is correct?

Accepted Answer

The magnetic field vector $$\vec{B} at $$any point is tangent to the magnetic field line at that point.

Question 12

A current-carrying wire is placed in a uniform magnetic field. The force on the wire is maximum when:

Accepted Answer

The wire is perpendicular to the magnetic field.

Question 13

A rectangular loop of wire with $$N$$ turns, area $$A$$, and current $$I is $$placed in a uniform magnetic field $$B. If $$the angle between the normal to the loop and the field increases, what happens to the torque on the loop?

Accepted Answer

The torque increases.

Question 14

Which of the following is a real-world application of the torque on a current-carrying coil?

Accepted Answer

Electric motor

Question 15

A wire of length $$0.5\ \mathrm{m}$$ carries a current of $$2\ \mathrm{A}$$ and is placed in a uniform magnetic field of $$0.3\ \mathrm{T} at an $$angle of $$30^\circ to $$the field. What is the magnitude of the force on the wire?

Accepted Answer

$$F = 0.15\ \mathrm{N}$$

Question 16

Which of the following best explains why a stationary charge does not experience a magnetic force?

Accepted Answer

The magnetic force depends on the velocity of the charge.

Question 17

The frequency $$f of $$the circular motion of a charged particle in a uniform magnetic field is:

Accepted Answer

$$f = \frac{|q|B}{2\pi m}$$

Question 18

In a mass spectrometer, the mass $$m of an $$ion is given by which of the following equations?

Accepted Answer

$$m = \frac{er^2$B^2$$}{2V}$

Question 19

Which of the following is true about the cyclotron period $$T$$ for a charged particle in a uniform magnetic field?

Accepted Answer

It does not depend on the speed of the particle.

Magnetic Fields (Chapter 27): Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards