Which one of the following materials cannot be used to make a lens?

Where should an object be placed in front of a convex lens to get a real image of the size of the object?

Which of the following can make a parallel beam of light when light from a point source is incident on it?

Under which of the following conditions a concave mirror can form an image larger than the actual object?

Rays from Sun converge at a point 15 cm in front of a concave mirror. Where an object should be placed so that size of its image is equal to the size of the object? 

What does negative sign in the value of magnification of a mirror indicate?

Between which two points of a concave mirror should an object be placed to obtain a magnification of - 3?

An image formed in a spherical mirror has magnification -2. Is the image real orvirtual?

A girl was playing with a thin beam of light from her laser torch by directing it from different directions on a convex lens held vertically. She was surprised to see that in a particular direction the beam of light continues to move along the same direction after passing through the lens. State the reason for this observation.

Give uses of concave mirror.

A concave mirror produces three times magnified (enlarged) real image of object placed at 10 cm in front of it. Where is the image located?

A ray of light travelling in air enters obliquely into water. Does the light ray bend towards the normal or from the normal?Why?

We wish to obtain an erect image of an object, using a concave mirror of focal length 15 cm. What should be the range of distance of the object from the mirror? What is the nature of image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.

A doctor has prescribed a corrective lens of power + 1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?

How do you find the rough focal length of a convex lens? Is the same method applicable to a concave lens?

Write laws of refraction. Explain the same with the help of ray diagram, when a ray of light passes through a rectangular glass slab.

(i) One half of a convex lens of focal length 10 cm is convered with a black paper. Can such a lens produce an image of a complete object placed at a distance of 30 cm from the lens? Draw ray diagram to justify your answer.
(ii) A 4 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20 cm. The distance of the object from the lens is 15 cm. Find nature, position and size of the image.

(a) Define optical centre of a spherical lens.
(b) A divergent lens has a focal length of 20 cm At what distance should an object of height 4 cm from the optical centre of the lens be placed so that its image is formed 10 cm away from the lens. Find the size of the image also.
(c) Draw a ray diagram to show the formation of image in above situation.

(a) State the laws of refraction of light. Give an expression to relate the absolute refractive index of a medium with speed of light in vacuum.
(b) The refractive indices of water and glass with respect to air are 4/3 and 3/2 respectively. If the speed of light in glass is \({ 2\times 10 }^{ 8 }\) ms^-1, find the speed of light in (i) air, (ii) water.

List the sign conventions for reflection of light by spherical mirrors. Draw a diagram and apply these conventions in the determination of focal length of a spherical mirror which forms a three times magnified real image of an object placed 16 cm in front of it.

Explain the following terms related to spherical lenses :
(a) (i) optical centre
      (ii) Centres of curvature
      (iii) principal axis
      (iv) aperture
      (v) principal focus
      (vi) focal length
(b) A converging lens has focal length of 12 cm. Calculate at what distance should the object be placed from the lens so that it forms an image at 48 cm on the other side of the lens.