Question

An object is placed at the centre of curvature of a concave mirror of radius of curvature 20cm and focal length 10 cm. At what distance from the pole will its image be formed?​

Answer 1

Answer:

The image is formed at a distance of 20cm from pole in front of mirror

Concept: Mirror formula

1/f = 1/v + 1/u

v = image distance

u = object distance

f = focal length of the mirror

f = (Radius of curvature)/2

Given: Focal length of the concave mirror = -10cm

Radius of curvature = -20cm

Object placed at a distance of 20 cm from the mirror pole.

To find: Image distance from pole (v)

Step by step explanation:

Object distance(u) = -20cm

Focal length of concave mirror = -10cm

we have mirror formula

1/f = 1/v + 1/u

Putting values in the above formula

1/(-10) = 1/v + 1/(-20)

1/(-10) + 1/(20) = 1/v

1/v = (-20 + 10)/200

1/v = -10/200

v = -20cm

Hence the image is formed at a distance of 20cm from pole in front of mirror

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