Page 2 - HA-refraction by spherical lens
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(b) B
(c) C
(d) D
4. The point in the lens through which light rays pass undeviated is known as
a) focus.
b) centre of curvature.
c) optical centre.
d) pole.
5. The middle of the concave lens is
a) thicker than its edges.
b) of the same thickness as its edges.
c) thinner than its edges.
d) thinner than one edge but thicker than the other.
Conceptual Questions
1. When sunlight is concentrated at a paper at the principal focus of a convex
lens, what happens to the paper? [Average]
2. Under what condition will a glass lens placed in a transparent liquid become
invisible? Describe and illustrate with a diagram, how we should arrange two
converging lenses so that a parallel beam of light entering one lens emerges as a
parallel beam after passing through the second lens. [Hots]
3 What is the suitable phenomenon for the working of a lens?
4. Which lens has a virtual focus and why?
5. A concave mirror and a convex lens are held separately in water. How will their
focal length be affected?
Objective Questions:
