JAMB Physics Past Questions & Answers - Page 239

1,191.

A lens of focal length 12.0cm forms an upright image three times the size of a real object. The distance between the object and the images is

A.

8.0cm

B.

16.0cm

C.

24.0cm

D.

32.0cm

Correct answer is D

F = 12cm, V = 3u

F = \(\frac{uv}{u + v}\)

12 = \(\frac{u\times 3u}{u + 3v}\)

u = 16cm, and v = 48cm

therefore, distance between u and v

v = 48 - 16 = 32cm

1,192.

Which of the following is true of sounds?

A.

sound travels faster in air at 20oC than at 30oC

B.

the frequency of a given sound wave changes when it crosses the boundary seperating two media

C.

the wavelength of a given sound wave in air decreases as the temperature increases

D.

sound waves cannot be reflected

Correct answer is C

No explanation has been provided for this answer.

1,193.

When two objects P and Q are supplied with the same quantity of heat, the temperature change in P is observed to be twice that of Q. The ratio of the specific heat capacity of P to Q is

A.

1 : 4

B.

4 : 1

C.

1 : 1

D.

2 : 1

Correct answer is C

\(\theta\)p = 2\(\theta\)q

mq = 2mp

Cp X mp X \(\theta\)p = Cq x mq x \(\theta\)q

\(\frac {C_pm_q\theta q}{C_qm_p \theta q}\) = \(\frac {\theta q \times 2mp}{2 \theta qmp}\)

\(\frac {C_p}{Cq}\) = \(\frac {2}{2}\)

1,194.

A gas occupies a volume of 300cm3at a temperature of 27oC. What is its volume at 54oC, when the pressure is constant?

A.

150cm3

B.

273cm3

C.

327cm3

D.

600cm3

Correct answer is C

\(\frac{V_1}{T_1}\) = \(\frac{V_2}{T_2}\)

\(\frac{300}{27 + 273}\) = \(\frac{V_2}{54 + 273}\)

V2 = 327cm3

1,195.

Which of the following properties makes metals ideal for cooking utensils?

A.

high coefficient of expansion

B.

good conduction of heat

C.

low specific heat capacity

D.

poor radiation of heat

Correct answer is B

No explanation has been provided for this answer.