Question

1.A virtual image is formed 20.5 cm from a concave mirror having a radius of curvature of 31.5 cm.

Answer 1

The position of the object is = -68cm

The magnification of the mirror= 0.3

Calculation of object distance

The image distance = 20.5cm

The focal length= R/2 = 31.5/2= 15.75

The object distance= ?

Using the lens formula,1/f = 1/v-1/u

1/u = 1/v- 1/f

1/u = 1/20.5 - 1/15.75

1/u = 0.0489- 0.0635

1/u = -0.0146

u = -68cm

The magnification of the mirror is image size/object size

= 20.5cm/-68cm

= 0.3

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