Question

Magnification of an object for a spherical mirror is +2.5, calculate the focal length of the mirror if the object is 6cm from the mirror. PLS ANSWER ONLY IF YOU KNOW

Answer 1

The mirror is definitely concave mirror, the object being placed between P and F and the image is formed behind the mirror.

Let us calculate image distance

-v/u = 2.5

-v = 2.5/ (-6) --- use sign convention.

v = 0.41 cm.

Now we need to find focal length

1/v + 1/u = 1/f

1/0.41 + 1/-6 = 1/f

= -6 + 0.41/ 2.5 = -5.59/2.5

Hence the focal length is - 0.44 cm.

Hope this helps. Please verify the calculations since these values are just the approximate.

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