A man 160 cm high stands in front of a plane mirror. His eyes are at a height of 150 cm from the floor. Then the minimum length of the plane mirror for him to see his full length image is

85 cm
170 cm
80 cm
340 cm

Solution

The minimum length of the mirror is half the length of the man. This can be proved from the fact that ∠i = ∠r.

A vessel is half filled with a liquid of refractive index m. The other half of the vessel is filled with an immiscible liquid of refrative index 1.5 m. The apparent depth of the vessel is 50% of the actual depth.Then m is

1.4
1.5
1.6
1.67

Solution

An air bubble in glass slab (m= 1.5) from one side is 6 cm and from other side is 4 cm.The thickness of glass slab is

10 cm
6.67 cm
15 cm
None of these

Solution

A glass slab of thickness 4 cm contains the same number of waves as 5 cm of water when both are traversed by the same monochromatic light. If the refractive index of water is 4/3,what is that of glass?

5/3
5/4
16/15
1.5

Solution

Light passes through a glass plate of thickness d and refractive index m. For small angle of incidence i, the lateral displacement is

id
id(μ-1)
\(\frac{id(\mu -1)}{\mu }\)
\(\frac{id\mu}{\mu -1}\)

Solution

A rectangular block of glass is placed on a mark made on the surface of the table and it is viewed from the vertical position of eye. If refractive index of glass be m and its thickness d,then the mark will appear to be raised up by

\(\frac{(\mu +1)d}{\mu }\)
\(\frac{(\mu -1)d}{\mu }\)
\(\frac{(\mu +1)}{\mu d}\)
\(\frac{(\mu -1)\mu}{d}\)

Solution

A lamp is hanging along the axis of a circular table of radiusr. At what height should the lamp be placed above the table,so that the illuminance at the edge of the table is ¹⁄₈ of that at its centre?

r/2
r/√2
r/3
r/√3

Solution

Two light sources with equal luminous intensity are lying at a distance of 1.2 m from each other. Where should a screen be placed between them such that illuminance on one of its faces is four times that on another face ?

0.2 m
0.4 m
0.8 m
1.6 m

Solution

A man’s near point is 0.5 m and far point is 3 m. Power of spectacle lenses required for (i) reading purposes, (ii) seeing distant objects, respectively, are

–2 D and +3 D
+2 D and –3 D
+2 D and –0.33 D
–2 D and + 0.33 D

Solution

A ray incident at 15° on one refracting surface of a prism of angle 60° suffers a deviation of 55°. What is the angle of emergence ?

95°
45°
30°
None of these

Solution

Here, i₁ = 15°, A = 60°, δ= 55°, i₂= e = ?

As i₁ + i₂= A + δ

i₂= A + δ – i₁= 60° + 55° – 15° = 100°.

UnAttempted

0

Attempted

0

Correct

0

Wrong

0

Complete