Question

A candle flame 3cm high is placed at a distance of 3m from a wall. How far from the wall must a concave mirror be placed so that it may form 9cm high image of the flame on the same wall?also find the focal length of the mirror

Answer 1

Answer:

Let distance between mirror and wall = Z. Then Z = Di (because image is on wall).

Then Z=3Do

But Do +3=Z→ Do + 3=3Do → 3=2Do → Do=1.5m and Di=4.5m

Therefore, mirror must be placed at 4.5 m from wall.

Using mirror equation, we can calculate focal length: 1/f=1/1.5+1/4.5 →

f=4.5/4=1.125m

Explanation:

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Answer 2

Answer:

3CM

Explanation: