Test Index

JAMB Physics 2021 Paper

© africaexams.com

Question : 38

Total: 40

The velocities of light in air and glass are 3.0 x 10

^8

^{-1}

^8

^{-1}

respectively. If the angle of refraction is 30º, the sine of the angle of incidence is?

0.33
0.50
0.67
0.75

Solution:

Concept:

Snell’s law links the ratio of sines to the ratio of wave speeds in two media.

Explanation:

Using Snell’s law:

\frac{\sin i}{\sin r} = \frac{v_{\text{air}}}{v_{\text{glass}}}

Given

v_{\text{air}} = 3.0 \times 10^{8}\,\mathrm{ms^{-1}}

and

v_{\text{glass}} = 2.0 \times 10^{8}\,\mathrm{ms^{-1}}

:

\frac{\sin i}{\sin 30^\circ} = \frac{3.0 \times 10^{8}}{2.0 \times 10^{8}} = 1.5

Since

\sin 30^\circ = 0.5

, multiply both sides:

\sin i = 1.5 \times 0.5 = 0.75

Therefore, the sine of the angle of incidence is

0.75

.

Answer:

D.

0.75

© africaexams.com

Go to Question:

Prev Question

Next Question