Question

Magnification is -3cm and focal length of a lens is 10 cm. Find v and u

Answer 1

Answer:

v = 40cm

u= -13.3cm

Explanation:

Given m=-3

we know that m=v/u

I.e -3= v/u

3u=v

I.e -3u =v........(1)

Given f= 10cm

1/f= 1/v - 1/u

1/(10) = -1/3u - 1/u

I.e

1/10=-1-3/3u

1/10=-4/3u

u= -40/3

u=-13.33 cm

v= -3×u

v=-3×-40/3

v= 40cm