﻿ ﻿Examination - Magnetism - Homework Helpers: Physics

## 7 Magnetism

### Chapter 7 Examination

Part I—Matching

Match the following terms to the definitions that follow.

a. Hans Christian Oersted

c. Joseph Henry

d. weber

e. volts

f. tesla

g. magnetic flux

h. magnetic declination

i. magnetic domains

_____1. Emf is actually not a force, and it is not measured in newtons. It is actually measured in these units.

_____2. Magnetic flux is measured in these units.

_____3. Magnetic field strength is measured in these units.

_____4. This American scientist independently discovered magnetic induction.

_____5. This Danish scientist showed that an electric current generates a magnetic field.

_____6. The product of the magnetic field and the area through which the magnetic field lines pass.

Part II—Multiple Choice

For each of the following questions, select the best answer.

7. Which of the following is not a ferromagnetic element?

a) iron

b) nickel

c) aluminum

d) cobalt

8. A magnetic field will be produced by

a) moving neutrons

b) moving protons

c) stationary electrons

d) stationary neutrons

9. An electron (e) and an oxide ion (O2–) are moving with the same velocity through a uniform magnetic field. Compared to the magnitude of the magnetic force experienced by the electron, the magnitude of the magnetic force experience by the oxide ion would be

a) the same

b) half as great

c) twice as great

d) four times as great

10. A charged particle moving through a magnetic field experiences a magnetic force. What is the angle between the magnetic field and the force on the particle?

a) 0°

b) 45°

c) 90°

d) 180°

11. An electron is moving through a magnetic field. If the velocity of the electron is doubled, the magnetic force experienced by the electron will

a) stay the same

b) double

c) triple

12. Which law states, “An induced emf gives rise to a current whose magnetic field opposes the change in magnetic flux that produced it.”

a) Lenz”s law

c) Coulomb”s law

d) Newton”s law

13. The instantaneous emf resulting from magnetic induction equals the rate of change of flux is:

a) Lenz”s law

c) Coulomb”s law

d) Newton”s law

14. In the following formula, the “N” stand for

a) voltage

b) emf

c) number of moles

d) number of loops

15. A wire loop is placed inside a magnetic field. The magnetic flux is maximized when the angle between the field lines and the surface of the area of the wire loop is:

a) 0°

b) 45°

c) 90°

d) 180°

16. An alpha particle (He2+) with a velocity of 2.6 × 106 m/s crosses a uniform magnetic field at an angle of 37.0° to the field lines and experiences a magnetic force of 1.4 × 10–3 N. Find the strength of the magnetic field.

17. Find the magnetic force on a 3.50 m current carrying wire that is parallel to the field lines of a 2.30 T magnetic field, when the wire draws a current of 2.0 A.

18. Calculate the emf generated in a coil with 12 turns of wire and an area of 1.30 m2 that was initially at rest in a uniform external magnetic field with a strength of 1.90 T, with the area of the loop orientated perpendicularly to the field lines, when it is pulled from the magnetic field in 0.30 seconds.

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