Ch 8 Making Use of Electricity Exercise 3

Which of the following are insulators?

(1) Chalk

(2) Pencil lead

(3) Rubber tubing

(4) Aluminium foil

• (1) and (3) only

• (1) and (4) only

• (1), (2) and (3) only

• (1), (2), (3) and (4)

Free electrons of a metal

• collide with each other.

• move around the nuclei of atoms.

• do not carry charges.

• move freely within the metal.

Which of the following statements about the current in a closed circuit is correct?

• Free electrons flow from the positive pole of the electric cell towards the negative pole.

• Free electrons flow from the negative pole of the electric cell towards the positive pole.

• Atoms flow from the positive pole of the electric cell towards the negative pole.

• Atoms flow from the negative pole of the electric cell towards the positive pole.

Which of the following statements about ammeter is/are correct?

(1) The larger the reading, the larger the electric current.

(2) Negative terminal should be connected to negative poles of electric cells.

(3) It measures the amount of energy supplied to the free electrons by the cell.

• (1) only

• (2) only

• (1) and (2) only

• (1), (2) and (3)

Which of the following instruments is used to measure current?

• A

• B

• C

• D

Which of the following does NOT make use of the heating effect of electric current?

• television

• toaster

• kettle

• heater

If we want to measure the voltage across the resistor, how should we connect the voltmeter?

• (1) only

• (2) only

• (1) and (3) only

• (2) and (3) only

The two voltmeters in the circuit below are identical. The voltage of the electric cell is 1.5 V. Which of the following statements about the circuit is correct?

• If voltmeter Q is disconnected, the reading of voltmeter P will become zero.

• The reading of voltmeter P is larger than the reading of voltmeter Q.

• The reading of voltmeter P is smaller than the reading of voltmeter Q.

• Voltmeters P and Q show the same readings.

Thomas designs a circuit as shown. Suppose the two light bulbs are identical and they are in series circuit with nichrome wire I and nichrome wire II respectively. In which of the following conditions will light bulb 1 be brighter than light bulb 2?

(1) Nichrome wire I is longer than nichrome wire 2.

(2) Nichrome wire I is thicker than nichrome wire 2.

(3) Nichrome wire I is replaced by a copper wire.

• (1) and (2) only

• (1) and (3) only

• (2) and (3) only

• (1), (2) and (3)

The following diagram shows a sliding rheostat connected to two electric cells and a light bulb. At which position of the sliding contact is the resistance of the sliding rheostat the greatest?

• A

• B

• C

• D