物理電磁感應 DSE、CE 選擇題（第 4 頁）

31.

Light coil XY suspended by strings next to a solenoid connected to a cell and switch S

A light coil of wire $XY$ is suspended by insulating string such that it can swing freely. A solenoid connected to a cell with a switch $S$ is placed near to the end $Y$ of the coil as shown. What would happen to the coil $XY$ just when the switch $S$ is closed ?

32.

Copper rod AB on two parallel wires in a magnetic field into the paper, pulled by force F to the right

A copper rod $AB$ is free to move on two parallel conducting wires. It is pulled by a force $F$ and moves in the direction shown in the figure. The magnetic field points into the paper. Which of the following statements is/are true ?

(1)A current will flow from

C

to

D

through

P

.

(2)A current will flow from

B

to

A

through

Q

.

(3)An induced voltage will be set up across

AB

.

33.

Which of the following devices is designed to convert mechanical energy into electrical energy ?

34.

Bar magnet moving along the diameter of a metal ring, with the N pole nearer the ring and the magnet moving to the left

The figure shows a bar magnet moving along the diameter of a metal ring. Which of the following will happen ?

35.

Simple generator: rectangular coil rotating between N and S poles with commutator, connected to a load

Which of the following statements concerning the generator shown in the figure is/are correct ?

(1)The direction of the current through the load reverses periodically.

(2)The maximum magnitude of the current depends on the speed of rotation of the coil.

(3)The maximum magnitude of the current depends on the resistance of the load.