JAMB Physics Past Questions & Answers - Page 99

491.

All electromagnetic waves in a vacuum have the same

A.

wavelength

B.

frequency

C.

speed

D.

amplitude

Correct answer is C

No explanation has been provided for this answer.

492.

An object is placed 20cm from a concave mirror of focal length 15cm. Calculate the linear magnification of the image formed

A.

0.5

B.

1.5

C.

2.0

D.

3.0

Correct answer is D

\(\frac{1}{U} + \frac{1}{V} = \frac{1}{F}\)

\(\frac{1}{V} = \frac{1}{F} - \frac{1}{U}\)

\(\frac{1}{V} = \frac{1}{15} - \frac{1}{20}\)

\(\frac{1}{V} = \frac{\text{4 - 3}}{60}\)


\(\frac{1}{V} = \frac{1}{60}\)

V = 60cm

M = \(\frac{V}{U} = \frac{60}{20}\)

M = 3.0cm

493.

Red light travels faster than blue light when both of them pass through a glass prism because the

A.

refractive index of red light is grester than that of blue light

B.

refractive index of blue light is greater than that of red light

C.

red light is more intense than the blue light

D.

blue light is more intense than the red light

Correct answer is D

No explanation has been provided for this answer.

494.

A girl standing some distance from the cliff claps her hands and hears the echo 0.8s later. calculate her distance from the cliff. [speed of sound in air = 320 ms-1]

A.

23m

B.

128m

C.

288m

D.

298m

Correct answer is B

V = \(\frac{2nx}{E}\)

= \(\frac{2 \times 1 \times X}{0.8} = 320\)

2x = 0.8 x 320

x = \(\frac{0.8 \times 320}{2}\)

= 128m

495.

When an air column is set into vibrations, the distance between two consecutive nodes of the resultant wave is

A.

one quarter of the wavelength

B.

half of the wavelength

C.

the wavelength

D.

twice the wavelength

Correct answer is B

No explanation has been provided for this answer.