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JAMB Physics Past Questions & Answers - Page 96

476.

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.

477.

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 = 2nxE

= 2×1×X0.8=320

2x = 0.8 x 320

x = 0.8×3202

= 128m

478.

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.

479.

A swimming pool is 2.1m deep. If it contains water of refractive index 1.3, calculate the apparent depth of pool

A.

3.4m

B.

2.7m

C.

1.6m

D.

0.8m

Correct answer is C

n = real depthapparent depth

1.3 = 2.1apparent

A.D = 2.11.3=1.6

480.

An object is placed 15cm from a diverging lens of focal length 12cm. The image of the object formed by the lens in

A.

real and 6.67cm from the lens

B.

virtual and 6.67cm from the lens

C.

real and 60.00cm from the lens

D.

virtual and 60.00cm from the lens

Correct answer is B

The focal length of a diverging lens is negative.

f = -12 cm; u = 15 cm.

f=uvu+v

12=15v15+v

12(15+v)=15v18012v=15v

180=15v+12v180=27v

v=18027=6.67cm

The image is virtual and 6.67 cm from the lens.