Magnetism 2,3

Which of the following terms correctly describes the shape of the magnetic field around a long, straight current-carrying wire?

• a. cylindrical

• b. parallel

• c. perpendicular

• d. elliptical

In what direction do compass needles deflect in relation to the concentric circles of the magnetic field that is found around a current carrying wire?

• a. away from the concentric circles

• b. perpendicular to the concentric circles

• c. toward Earth’s North Pole irrespective of the concentric circles

• d. tangential to the concentric circles

The right-hand rule states that the thumb of the right hand is to be placed in what direction when grasping a wire?

• a. in a direction opposite of the current

• b. in the direction of the current

• c. in the direction of Earth’s magnetic north pole

• d. none of the above

According to the right-hand rule, in what direction will the fingers curl?

• a. in the direction of the current

• b. in the direction of the magnetic field, B

• c. in the direction of the magnetic field’s movement

• d. in the direction of the magnetic field’s force

Which of the following statements about the magnetic field, B, around a current-carrying wire is not true?

• a. B is proportional to the current in the wire.

• b. B is inversely proportional to the distance from the wire. .

• c. The lines of B form concentric circles about the wire

• d. B is independent of the current in the wire.

The magnetic field of a current loop is most similar to that of a(n)

• a. horseshoe magnet.

• b. circular magnet.

• c. bar magnet.

• d. irregular magnet.

The strength of a solenoid can be increased by

• a. increasing the current.

• b. increasing the number of wire loops.

• c. inserting an iron rod through the center of the coil.

• d. all of the above

Which of the following statements about the magnetic field lines of a solenoid is not true?

• a. The field lines inside a solenoid point in the same direction and are nearly parallel.

• b. The field lines inside a solenoid are uniformly spaced and close together.

• c. The field lines outside a solenoid are uniformly spaced but further apart.

• d. The field lines outside a solenoid do not always point in the same direction.

What is a solenoid? What is a solenoid called when an iron rod is inserted in its center? What advantage is gained by this addition?

Draw magnetic field lines around the figure below and label its north and south magnetic poles.