物理 1982 年 DSE、CE 選擇題（第 2 頁）

11.

The following data shows the thermal properties of four substances $P$ , $Q$ , $R$ and $S$ :

Substance	$P$	$Q$	$R$	$S$
Melting point	$40$ K	$98$ K	$114$ K	$270$ K
Boiling point	$280$ K	$880$ K	$180$ K	$370$ K
Average specific heat capacity in $\mathrm{J\,kg^{-1}\,{}^\circ C^{-1}}$	$800$	$1200$	$226$	$40$
Specific latent heat of fusion in $\mathrm{J\,kg^{-1}}$	$2\times10^4$	$11\times10^4$	$5\times10^4$	$33\times10^4$
Specific latent heat of vaporization in $\mathrm{J\,kg^{-1}}$	$30\times10^4$	$34\times10^4$	$40\times10^4$	$230\times10^4$

When the temperature of each substance is increased from $250$ K to $400$ K, which one will absorb the greatest amount of energy ?

12.

Points P, Q, R, S, lens position L, focus F and a real image I on the principal axis

A real image of an object is formed at $I$ by a lens placed at $L$ . If the focus of the lens is at $F$ , the object must have been placed near to

13.

Lamp, convex lens L and screen with a sharp image formed on the screen

A convex lens $L$ is placed between a screen and a lamp. A sharp image is formed on the screen as shown in the above figure. Which of the following statements concerning the image are correct ?

(1)The image is larger than the object.

(2)The image is real.

(3)The image is inverted.

14.

The table below shows the voltage and power rating for various electrical appliances. Which of the electric appliances has the smallest working resistance ?

Appliance	Voltage	Power / W
Air-conditioner	200	2000
Television	200	250
Heater	100	2000
Hair-dryer	100	20

15.

Lamp L1 in the top branch, lamps L2 and L3 in a middle branch, cell in the bottom branch

In the circuit shown, the cell has negligible internal resistance. If the lamp $L_3$ burns out, then

16.

A set of Christmas tree lights consists of $20$ bulbs in series. Each bulb has a rating of " $10$ V $5$ W". One of the bulbs burns out and Jimmy goes to buy a replacement. When he gets back, he finds that although the new bulb is marked $5$ W, it looks dimmer than the others when the lights are turned on. The most probable reason for this is that the new bulb

17.

Fifteen bulbs, each labelled ' $200$ V $60$ W', are connected in parallel to a $200$ V supply. Which of the following fuses should be used in the circuit ?

18.

Suppose you were given four similar lamps and a battery. Which of the following ways of connecting the lamps to the battery would give the maximum brightness overall ?

Four circuits A to D, each connecting four lamps to a battery in different series/parallel arrangements

19.

In the circuit shown, the cell has negligible internal resistance. The two resistors $R$ are identical. If the power dissipated in the circuit is $P$ when $K$ is open, find the power dissipated when $K$ is closed.

Cell in series with a resistor R, then a second resistor R in parallel with a switch K

20.

Battery with three resistors and a voltmeter connected across one resistor

In the given circuit diagram, the battery has a voltage of $6$ V and negligible internal resistance. The three resistors are identical and the voltmeter has the same resistance as each resistor. What is the reading on the voltmeter ?