Question

Object is placed at a distance of 4 cm from focus of concave mirror. Then image is formed at a distance of 16 cm from the focus on same side. What is the focal
length of mirror ?

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Answer 1

Answer:

1/f = 1/u + 1/v

here u = f+4, and v = f+16

1/f = 1/(f+4) + 1/(f+16)

1/f = (f+16+f+4)/((f+4)(f+16))

simplifying it, we get,

f² = 64

f = √64 = 8

f = 8cm.

Step-by-step explanation:

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