Question

The relation between focal length f and magnification m , image distance v of a spherical mirror of small aperture is given by :

1: ​mf = f-v
2: mf = f+v
3: mf = v-f
4: m = f-v

Which option is correct??

Answer 1

Answer:

m = v/u

So, u = v/m

By mirror formula, 1/f = 1/v + 1/u

So, 1/f = 1/v + m/v

=> v = f(m+1)

=> v = mf + f

=> mf = v-f

Option 3: is correct