Question
Sun September 06, 2009 By:

please solve it!

Expert Reply
Tue September 08, 2009

Given: m = 1/2; u = - 60 cm;

since m = - v / u;

v = - m u = 30 cm

using mirror formula

(1 / f) = (1 /  v) + (1 / u)

(1 / f) = (1 / 30) - (1 / 60)

f = 60 cm

In the second case -

m = 1/ 3;

m = - v / u;

v = - u / 3;

Again using mirror formula

(1 / f) = (1 /  v) + (1 / u)

(1 / 60) = (- 3 / u) - (1 / u)

(1 / 60) = - 4 / u

u = - 240 cm

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