A spherical lens is said to be thin lens when its ______ is negligible as compared to its radius of curvature.

The bulged out spherical surface is a ____ surface.

1. Concave
2. Convex
3. Plane
4. Cannot say

The point where a ray of parallel beam of light converges to after refraction through a convex lens is called ____.

1. Center of curvature
2. Focus
3. Optical center
4. Pole 

A light ray enters medium 2 from medium 1. If the medium 2 has a refractive index less than medium 1, the light ray would _____ on entering medium 2.

1. Bend towards the normal 
2. Bend away from the normal
3. Not bend at all
4. Bend by an angle of 45 degrees

Which of the following objects does not refract light?

1. Concave lens
2. Concave lens
3. Glass slab
4. Concave mirror

The distance between the focus and the optical center is called the ____.

1. Optical distance
2. Focal point
3. Focal length
4. Radius of curvature

Which of the following can be used to light up a fire?

1. Concave lens
2. Convex lens
3. Plane mirror
4. Convex mirror

Refractive index is a property of ____. 

1. A medium 
2. A pair of mediums 
3. Infinitely many mediums
4. A substance 

Principal axis passes through _____.

1. F1 and F2
2. C1 and C2
3. Optical center
4. All of the above

A biconcave/biconvex lens has ____ focal point(s) and ____ center(s) of curvature.

1. 1,1
2. 2,2
3. 1,2
4. 2,1

Light travelling from air to which of the following mediums bends towards the normal?

1. Glass 
2. Diamond 
3. Ruby 
4. All of these 

Which of the following mediums (with refractive indices given) creates the highest bending of light? 

1. 1.5
2. 1.3
3. 2.4
4. 1.8

The central point of a lens is called its _____.

1. Pole
2. Center of curvature
3. Optical center
4. Focal point

The diameter of the outer edge of a lens is called the ____.

1. Diameter of curvature
2. Radius of curvature
3. Aperture
4. Focal length

Analyse from the picture and find out the substance that has the highest refractive index.