物理電路 DSE、CE 選擇題（第 7 頁）

61.

The potential difference between two points $X$ and $Y$ in a circuit is $10$ V. Which of the following must be true ?

62.

Battery with ammeters A1, A2, A3, resistors and a switch S in parallel with one resistor

In the circuit above, what happens to the readings of the three ammeters if switch $S$ is closed ?

$A_1$	$A_2$	$A_3$
increases	increases	increases
remains unchanged	becomes zero	increases
increases	increases	becomes zero
decreases	increases	becomes zero

63.

6 V battery in series with a 10 ohm resistor and a 5 ohm resistor

In the circuit shown, what is the power dissipated in the $10\ \Omega$ resistor ?

64.

Which of the following is/are vectors ?

(1)momentum

(2)power

(3)voltage

65.

Battery with resistors P and Q in series and resistor R with switch S in parallel with Q

In the above circuit, $P$ , $Q$ and $R$ are identical resistors. Which of the following is true when switch $S$ is closed ?

66.

The following diagrams show three networks consisting of different resistors.

Network (1): 1 ohm, 1 kilohm and 1 megohm in parallel; (2): the three in series; (3): 1 megohm in parallel with 1 ohm, in series with 1 kilohm

Arrange the above networks in descending order of equivalent resistances :

67.

3 V battery, switch S, voltmeter V1 across the battery and switch, 10 ohm and 20 ohm resistors in series with voltmeter V2 across the 20 ohm resistor

In the circuit shown, what are the readings of voltmeters $V_1$ and $V_2$ if switch $S$ is closed ?

	Voltmeter $V_1$	Voltmeter $V_2$
	$0$ V	$2$ V
	$0$ V	$3$ V
	$1$ V	$2$ V
	$3$ V	$0$ V

68.

6 V battery with 4 ohm resistor, then 3 ohm and 1 ohm resistors in series (point X between them) in parallel with a 4 ohm resistor, point Y at the junction

In the circuit shown, the potential difference between $X$ and $Y$ is

69.

Cell with bulbs L1, L2 and L3 and a switch S in the L2 branch

In the circuit shown, $L_1$ , $L_2$ and $L_3$ are identical light bulbs. Which of the following statements is/are correct when the switch $S$ is closed ?

(1)The brightness of

L_1

decreases.

(2)

L_2

and

L_3

are of the same brightness.

(3)

L_1

is brighter than

L_2

.

70.

An electric heater takes a time $T$ to boil a kettle of water when connected to a $200$ V source. What will be the time required to boil the same kettle of water when the heater is connected to a $100$ V source ? (You may assume that the resistance of the heater remains unchanged.)