Question

An object 4cm high is places ay a distance of 16cm from a concave mirror produces a real image 5cm high (i)find the position of image (ii)what is the final length of the mirror.

Answer 1

Ans.

u = -16 CM

O = 4 CM

I = -5cm

(i) Position of image (v),

I/O = -v/u = |m|

I/O = -5/4

-5/4 = -(v/-16)

-5/4 = v/16

v = -20 CM

(ii) Focal Length (f),

1/v + 1/u = 1/f

{1/-20} + {1/-16} = 1/f

-1/20 - 1/16 = 1/f

-4-5/80 = 1/f

-9/80 = 1/f

f = -80/9 CM