Question

if v = -30 cm and u = -10 cm what is the focal length of the mirror ​

Answer 1

Answer:

v = -30 cm

u= -10 cm

f = ?

In mirror,

1/f = 1/v + 1/u

1/f = 1/(-30) + 1/(-10)

1/f = -1/30 + -1/10

= -1/30 +-3/30(LCM of10,30 is 30)

1/f = -4/30

By doing cross multiplication

f = -30/4 = -7.5 cm

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