物理電路 DSE、CE 選擇題（第 6 頁）

51.

Which of the following pairs of physical quantities has the same units ?

52.

Cell and 10 ohm resistor between P and Q, with 5 ohm resistor and ammeter A1 and 10 ohm resistor and ammeter A2 in parallel branches

In the above circuit, the reading of ammeter $A_1$ is $0.6$ A. Find the p.d. between points $P$ and $Q$ .

53.

Battery with ammeter A2, bulb and ammeter A1 in one branch, bulb and switch S in another branch, and a voltmeter across the supply

In the circuit above, the ammeters have negligible resistance. Which of the following statements are true if switch $S$ is closed ?

(1)The reading of ammeter

A_1

decreases.

(2)The reading of ammeter

A_2

increases.

(3)The reading of the voltmeter remains unchanged.

54.

Which of the following is a correct unit for the corresponding physical quantity ?

	Physical quantity	Unit
	Work	watt
	Electromotive force	newton
	Momentum	newton second
	Heat capacity	joule per kilogram

55.

A student uses an ammeter and a voltmeter to find the resistance of a light bulb. He incorrectly connects the circuit as shown. Which of the following is the most probable outcome ?

6 V battery with a voltmeter in series, a light bulb in parallel with the voltmeter branch and an ammeter in parallel

56.

6 V battery with a 4 ohm resistor in series with two 4 ohm resistors in parallel between X and Y

Find the p.d. between $X$ and $Y$ in the above circuit.

57.

Battery with switch S in parallel with bulb L1, bulb L2 and bulb L3

In the above circuit, all the light bulbs are identical. What happens to the brightness of the bulbs $L_1$ , $L_2$ and $L_3$ if switch $S$ is closed ?

$L_1$	$L_2$	$L_3$
decreases	increases	remains unchanged
increases	remains unchanged	increases
decreases	remains unchanged	remains unchanged
remains unchanged	decreases	increases

58.

Battery with ammeter A3, two resistors in series with ammeter A1, and a resistor with ammeter A2 in a parallel branch

In the circuit shown above, all resistors are identical and the ammeters are of negligible resistance. If the readings of ammeter $A_1$ is $2$ A, find the readings of ammeters $A_2$ and $A_3$ .

	$A_2$	$A_3$
	$2$ A	$2$ A
	$2$ A	$4$ A
	$4$ A	$2$ A
	$4$ A	$6$ A

59.

Which of the following circuits can be used to measure the resistance of the light bulb ?

Four circuits A to D with a battery, light bulb, ammeter and voltmeter connected in different ways

60.

Battery with bulb L1 in series with bulbs L2 and L3 in parallel

In the circuit, $L_1$ , $L_2$ and $L_3$ are identical light bulbs. Which of the following statements is/are true ?

(1)

L_2

and

L_3

have the same brightness.

(2)

L_1

is brighter than

L_2

.

(3)The power dissipated in

L_1

is equal to the sum of powers dissipated in

L_2

and

L_3

.