JAMB Physics Past Questions & Answers - Page 236

1,176.

If the fundamental frequency of a closed pipe organ on a day when the speed of sound is 340ms-1 is 170Hz, then the length of the pipe is

A.

50cm

B.

70cm

C.

100cm

D.

150cm

E.

200cm

Correct answer is A

\(\lambda\) = \(\frac{v}{f}\)

= \(\frac{340}{170}\)

= 2m ; for closed pipe

L = \(\frac{1}{4}\)\(\lambda\)

= \(\frac{1}{4}\) x \(\frac{2}{1}\)

= 0.5m

= 50cm

1,177.

When a sound wave passes from air into water its

A.

speed and frequency increases but its wavelength remains the same

B.

speed and wavelength increases but its frequency remains the same

C.

speed decreases

D.

speed remains the same but its frequency and wavelength change

E.

speed increases but its frequency and wavelength decreases

Correct answer is C

No explanation has been provided for this answer.

1,178.

In order to find the depth of the sea, a ship sends out a sound wave and receives an echo after one second. If the velocity of sound in water is 1500ms-1, what is the depth of the sea?

A.

0.75km

B.

1.50km

C.

2.20km

D.

3.00km

E.

3.75km

Correct answer is A

Echo time = 1 \(\div\) 2 = 0.5sec

depth = velocity x time

= 1500 x 0.5

= 750m = 0.75km

1,179.

Which of the following phenomena CANNOT be explained by the molecular theory of matter?

A.

Expansion

B.

Conduction

C.

Convection

D.

Radiation

E.

Evaporation

Correct answer is D

No explanation has been provided for this answer.

1,180.

Which of the following statements are NOT correct?

A.

boiling occurs when the saturated vapour pressure of the liquid involved equals the external pressure

B.

both the boiling point and the saturated vapour pressure of a given liquid depends on the external pressure

C.

the saturated vapour presssure rises with increase in temperature

D.

the saturated vapour pressure is independent of the volume available for the vapour

E.

it is possible to boil water at a lower temperature than 100oC at high altitude

Correct answer is D

The saturated vapour pressure is dependent on the temperature of the liquid and not on the volume.