An object is placed at a distance 24cm from the lens and then at a distance of 16cm from the lens. The magnification of the image formed in both cases is same. What is the focal length of the lens.
22cm
20cm
18cm
none of these
When the ray of light is incident from a denser medium having refractive index 2.What should be the angle of incidence for the ray to go out of the medium?
less than 30o
less than 45o
less than 60o
less than 90o
Which type of mirror always forms a diminished and virtual image of the real object?
Convex
Concave
plane
parabolic
A spherical mirror produces lateral magnification M what is the longitudinal magnification produced by it?
M2
M
M1/2
M3/2
A beam of light passes from air to glass, how does the speed of light vary?
decreases
increases
remains unchanged
It may decrease or increase depending upon the colour.
A ray of light passes through a plane glass a slab of thickness t and refractive index μ= 1.5. The angle between the incident ray and emergent ray will be
00
300
450
600
The index of refraction of diamond is 2.0, velocity of light in diamond in cm per second is approximately.
6x1010
3.0x1010
2x1010
1.5x1010
It is desired to photograph the image of an object placed at a distance 3m from the plane mirror.The camera,which is at a distance of 4.5m from the mirror should be focussed for a distance of:
3m
4.5m
6m
7.5m
Convex lens of power 4D and a concave lens of power 3D are placed in contact. What is the equivalent power of the combination?
7D
4/3 D
1D
3/4D
A lens behaves as a converging lens in air and a diverging lens in water. The refractive index of the material is
Equal to unity
Equal to 1.33
Between unit and 1.33
greater than 1.33
