物理電路 DSE、CE 選擇題

1.

The figure below shows the current-voltage ( $I$ - $V$ ) graphs of two resistors $P$ and $Q$ .

I against V graph with two straight lines through the origin, P steeper than Q

Which of the following statements about the two resistors are correct ?

(1)Both of them obey Ohm's law.

(2)The resistance of

P

is greater than that of

Q

.

(3)If they are connected in parallel to a battery, the current passing through

P

will be greater than that passing through

Q

.

2.

Which of the following resistor networks gives the largest equivalent resistance across $PQ$ if all the resistors have the same resistance ?

Four ring-shaped resistor networks A to D with terminals P and Q: A has 2 resistors per side, B pentagon, C hexagon with P and Q adjacent, D hexagon with P and Q opposite

3.

Battery with 6 ohm resistor, ammeter, 6 ohm resistor, and 3 ohm resistor with switch S

In the circuit shown, the ammeter reading is $1.0$ A when $S$ is open. What is the ammeter reading when $S$ is closed ?

4.

Battery, ammeter and bulb X in series with bulb Y and a voltmeter across the combination

In the circuit shown, both bulbs $X$ and $Y$ light up normally. Both the ammeter and the voltmeter readings are non-zero. Which of the following will cause the ammeter reading to drop to zero while the voltmeter reading is still non-zero ? Assume meters are ideal.

5.

A car has two doors and an indicator lamp is installed to act as a car door warning signal. When either or both doors are open, the lamp lights up. A student designs four different circuits for this application. A switch is installed in each door. The switch is open when the car door opens. Which of the following circuits is correct ?

Four circuits A to D with a battery, resistor, lamp and two door switches

6.

1.5 V cell with a switch and a light bulb in series, voltmeter P across the switch and voltmeter Q across the bulb

In the circuit above, voltmeters $P$ and $Q$ of very high resistance are connected across the switch and the light bulb respectively. What are the voltmeter readings when the switch is open ?

	reading of $P$ / V	reading of $Q$ / V
	$0$	$0$
	$0$	$1.5$
	$1.5$	$0$
	$1.5$	$1.5$

7.

12 V battery with bulb X in series with bulbs Y and Z in parallel, points P, Q, R, S marked

Three identical bulbs $X$ , $Y$ and $Z$ are connected to a $12$ V battery in the circuit above. Which of the following statements are correct ?

(1)The voltage across

PQ

is greater than

6

V.

(2)The voltage across

QS

is zero.

(3)If

Y

burns out and becomes open circuit,

Z

becomes brighter.

8.

Resistor network PQRS with 3 ohm, 2 ohm and 1 ohm resistors, battery and ammeter, with wires X and Y to be connected

In the circuit shown, wires $X$ and $Y$ are to be connected to two points in the resistor network $PQRS$ . Across which two points should $X$ and $Y$ be connected so that the ammeter reading will be a minimum ?

9.

Two identical resistors are connected in series in the circuit shown. What are the readings of the voltmeter when $S$ is open and when $S$ is closed respectively ?

12 V battery with two resistors in series, switch S, and a voltmeter across the second resistor and the switch

	$S$ is open	$S$ is closed
	zero	$6$ V
	zero	$12$ V
	$12$ V	$6$ V
	$12$ V	$12$ V

10.

Table of three ways of connecting a circular loop, with equivalent resistances X, Y and Z

A circular loop is made of uniform resistance wire. Let $X$ , $Y$ and $Z$ be the equivalent resistance of the loop when connected as shown above. Which of the following is correct ?