JAMB Physics Past Questions & Answers - Page 185

921.

The speed of light in air is 3 x 108ms-1. If the refractive index of light from air-to-water is \(\frac{4}{3}\), then which of the following is the correct value of the speed of light in water?

A.

4 x 108ms-1

B.

2.25 x 108ms-1

C.

\(\frac{4}{9}\) x 108ms-1

D.

2.25 x 102ms-1

E.

4.33 x 108ms-1

Correct answer is B

Air to water = \(\frac{\text{speed in air}}{\text{speed in water}}\)

\(\frac{4}{3}\) = \(\frac{3 \times 10^8}{V}\)

4V = 3(3 x 108)

V = \(\frac{3(3 \times 10^8)}{4}\)

V = 2.25 x 108ms-1

923.

Which of the following electromagnetic waves has the shortest wavelength?

A.

Radio waves

B.

X-rays

C.

Infra-red

D.

Blue light

E.

Ultraviolet

Correct answer is B

No explanation has been provided for this answer.

924.
925.

Which of the following statements is true? The frequency of a vibrating string is

A.

proportional to its length

B.

inversely proportional to the tension within it

C.

proportional to the aptitude of vibration

D.

inversely proportional to its cross-section

E.

proportional to the square root of the tension within it

Correct answer is E

No explanation has been provided for this answer.