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JAMB Physics Past Questions & Answers - Page 238

1,186.

A pencil is placed vertically between a concave mirror and its focal point. The image of the pencil in the mirror will be

A.

real, inverted and diminished

B.

virtual, inverted and enlarged

C.

real, erect and enlarged

D.

virtual, erect and enlarged

Correct answer is D

No explanation has been provided for this answer.

1,187.

What is the effect of the increase in the size of the hole of a pin-hole camera on the image? it

A.

gives a blurred image

B.

corrects for chromatic aberration

C.

magnifies the image

D.

brings the image into a sharper focus

Correct answer is A

No explanation has been provided for this answer.

1,188.

A dentist obtains a linear magnification of 4 of a hole in a tooth by placing a concave mirror at a distance, of 2.0cm from the tooth. The radius of Curvature of the mirror is

A.

5.3cm

B.

3.2cm

C.

2.7cm

D.

1.6cm

Correct answer is B

v = 4u, if u = 2cm, v = 8cm

F = uvu+v

= 2×82+8

= 1.6cm

r = 2F

= 2 x 1.6

= 3.2cm

1,189.

If the refractive index of glass is 1.5, what is the critical angle at the air-glass interface?

A.

sin-112

B.

sin-123

C.

sin-134

D.

sin-189

Correct answer is B

sin ic 1n = 115

i = sin-1115

= sin-11015

= sin-123

1,190.

In which of the following arrangements is the wavelength in an increasing order?

A.

Gamma rays, infra-red rays, x-rays, radiowaves

B.

Gamma rays, x-rays, infra-red ray, radiowaves

C.

Radiowaves, x-rays, gamma ray, infra-red rays

D.

Infra-red rays, radiowaves, x-rays, gamma rays

Correct answer is B

No explanation has been provided for this answer.