Question 1

Which statement best describes the behavior of magnetic poles when a permanent magnet is cut in half?

Accepted Answer

Each half will have both a north and a south pole.

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 true about magnetic field lines around a bar magnet?

Accepted Answer

They form closed loops from the north pole to the south pole outside the magnet and from south to north inside.

Question 4

A long, straight wire carries a current $$I$$ out of the page. What is the direction of the magnetic field at a point to the right of the wire?

Accepted Answer

Clockwise around the wire

Question 5

The magnetic field at a distance $$r$$ from a long, straight conductor carrying current $$I is $$given by:

Accepted Answer

$$B = \dfrac{\mu_0$ I}{2\pi r}$$

Question 6

A proton moves with velocity $$\vec{v}$$ parallel to a uniform magnetic field $$\vec{B}. $$What is the magnetic force on the proton?

Accepted Answer

Zero

Question 7

Which of the following materials exhibits ferromagnetism?

Accepted Answer

Iron

Question 8

A circular loop of radius $$a$$ carries a current $$I. $$What is the magnetic field at the center of the loop?

Accepted Answer

$$B = \dfrac{\mu_0$ I}{2a}$$

Question 9

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

Accepted Answer

$$F = ILB \sin 	heta$$

Question 10

Which law states that the net magnetic flux through any closed surface is zero?

Accepted Answer

Gauss's Law for Magnetism

Question 11

A solenoid has $$N$$ turns per unit length and carries a current $$I. $$What is the magnetic field inside the solenoid?

Accepted Answer

$$B = \mu_0$ N I$$

Question 12

A charged particle of mass $$m$$ and charge $$q$$ moves perpendicular to a uniform magnetic field $$B$$ with speed $$v. $$What is the radius of its circular path?

Accepted Answer

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

Question 13

Which of the following best explains why the magnetic force does no work on a charged particle?

Accepted Answer

The force is always perpendicular to the displacement.

Question 14

A current-carrying wire is placed parallel to another wire carrying current in the same direction. What is the nature of the force between the wires?

Accepted Answer

They attract each other.

Question 15

A rectangular current loop is placed in a uniform magnetic field. What is the maximum torque experienced by the loop?

Accepted Answer

$$	au_{max} = IAB$$

Question 16

Which of the following statements about magnetic monopoles is correct?

Accepted Answer

They are always found in pairs in nature.

Question 17

A velocity selector uses perpendicular electric and magnetic fields. For a particle to pass through undeflected, its velocity must be:

Accepted Answer

$$v = \dfrac{E}{B}$$

Question 18

Which property distinguishes paramagnetic materials from ferromagnetic materials?

Accepted Answer

Paramagnetic materials align their magnetic moments only in the presence of an external field.

Question 19

What is the SI unit of magnetic flux?

Accepted Answer

Weber (Wb)

Question 20

A wire of length $$0.70 m $$carries a current of $$50 A $$and makes a $$30^\circ$$ angle with a uniform magnetic field. If the force on the wire is $$17.5 N$$, what is the magnitude of the magnetic field?

Accepted Answer

$$B = 0.5 T$$

Magnetic Field: Properties, Sources, and Effects (Chapter 29 Study Notes)

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