物理電路 DSE、CE 選擇題（第 11 頁）

101.

Suppose that it takes $8$ minutes to boil a kettle of water. If the heating coil of the kettle is shortened to half its original length and the supply voltage remains unchanged, then to boil the same amount of water will take

102.

Resistor network of five 2 ohm resistors between points A, B, C and D

The diagram shows a network of resistors, where the resistance of each resistor is $2\ \Omega$ . What are the equivalent resistances across $AB$ and $AD$ respectively ?

	$AB$	$AD$
	$1.67\ \Omega$	$1.00\ \Omega$
	$1.67\ \Omega$	$1.67\ \Omega$
	$1.67\ \Omega$	$3.67\ \Omega$
	$2.50\ \Omega$	$1.00\ \Omega$

103.

Circuit with resistors R1 and R2, ammeters A1 and A2, a 5000 ohm resistor between points A and B and a battery

In the circuit shown, ammeter $A_1$ reads $2$ mA and ammeter $A_2$ reads $8$ mA. What is the voltage across $AB$ ?

104.

2 V cell connected across a 4 ohm resistor and a 2 ohm resistor in parallel

In the circuit shown, what is the power dissipated in the $4\ \Omega$ resistor ?

105.

In the circuit shown, the battery has an e.m.f. of $6$ V with negligible internal resistance. Four resistors are connected to the battery as shown in the figure.

Two parallel branches (4 ohm and 8 ohm in series, 8 ohm and 4 ohm in series) joined at points P and Q, connected to a 6 V battery

What is the potential difference between points $P$ and $Q$ ?

106.

Cell, two resistors R, an ammeter and a switch K: one R in series with the ammeter, the other R with switch K in a parallel branch

Two identical resistors $R$ , an ammeter, a switch $K$ and a cell are connected as shown. When $K$ is open, the ammeter reading is $1$ A. When $K$ is closed, the reading will

107.

2 V cell with ammeter A and switch K in series, voltmeter V in parallel with that branch, and a 100 ohm resistor in series

In the circuit shown, $V$ is a voltmeter of high internal resistance and $A$ is an ammeter of low internal resistance. What is the voltmeter reading when (a) switch $K$ is open, and (b) switch $K$ is closed ?

	$K$ open	$K$ closed
	$0$ V	$0$ V
	$0$ V	$2$ V
	$1$ V	$1$ V
	$2$ V	$0$ V