Question

an object is placed in front of a concave mirror of focal length 20 the image formed is 3 times the size of the object . claculate two posible distances of the object from the mirror. ITS LONG SO I'LL GIVE YOU FEW MORE POINTS THAN USUAL:)

Answer 1

Answer:

possible distance is 20×3

=60

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Answer 2

Question:-

an object is placed in front of a concave mirror of focal length 20 the image formed is 3 times the size of the object . claculate two posible distances of the object from the mirror

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(a) 80/3 cm

(b) -40/3 cm

● Explanation -

Given that, image size is 3 times object size. Thus magnification is ±3.

(a) For M = +3,

v/u = +3

v = 3u

Using mirror formula,

1/f = 1/v + 1/u

1/20 = 1/3u + 1/u

Solving this,

u = 80/3 cm

(b) For M = -3,

v/u = -3

v = -3u

Using mirror formula,

1/f = 1/v + 1/u

1/20 = 1/-3u + 1/u

Solving this,

u = -40/3 cm

hope it helps you..