Question 251:

• JAMB 1983

The refractive index of liquid is 1.5. If the velocity of light in vacuum is 3.0 x 10⁸ms^-1, the velocity of light in the liquid is

A. 1.5 x 10⁸m^-1
B. 2.0 x 10⁸m^-1
C. 3.0 x 10⁸m^-1
D. 4.5 x 10⁸m^-1
E. 9.0 x 10⁸m^-1

Question 252:

• JAMB 1983

If relative density of a metal is 19, what will be the mass of 20cm³ of the metal when immersed in water?

A. 380g
B. 400g
C. 360g
D. 39g
E. 180g

Question 253:

• JAMB 1983

Which of the following statements is true about liquid pressure is NOT correct? The pressure

A. At a point in a liquid is proportional to the depth
B. At any point in a liquid is the same at the same level
C. Is exerted equally in all directions at any point
D. Of a liquid at any point on the wall of its container acts in a direction perpendicular to the wall
E. At a particular depth depends on the shape of the vessel

Question 254:

• JAMB 1983

A ship travelling towards a cliff receives the echo of its whistle after 3.5 seconds. A short while later, it receives the echo after 2.5 seconds. If the speed of sound in air under the prevalling condition is 250ms ^-1, how much closer is the ship to the cliff?

A. 10m
B. 125m
C. 175m
D. 350m
E. 1,000m

Question 255:

• JAMB 1983

which of the following is NOT correct? i. the pitch of a sound note depends on the frequency of vibrations. ii. the intensity of a sound note is proportional to the amplitude of vibrations. iii. beats are produced by two sources of sound because one wave is travelling faster than the other. iv. when two sources of sound of frequencies 500Hz and 502Hz are sounded together, a beat frequency of 2Hz is observed. v. the first harmonic of a tone have double the frequency of the fundamental note.

A. I and ii
B. Ii and iii
C. I and iii
D. Iii and iv
E. Iv and v