Q3 of 117 Page 10

Find the power of a concave lens of focal length 2 m.

The focal length of a concave lens is considered negative and hence written with a minus sign. So, focal length of concave lens, f = -2 m

Now, Power, P =

Thus, Power, P = -0.5D, Where D stands for Dioptre

Define the principal focus of a concave mirror.

The magnification produced by a plane minor is +L What does this mean ?

What does the negative sign in the value of magnification produced by a mirror indicates about an image?

Given below are refractive indices of a few material media.

Rock salt - 1.54

Ice - 1.31

Dense flint glass - 1.65

Crown glass - 1.52

Arrange the media in the ascending order of optical density.