Question

The power of lens is +5 D. If an object is placed 30 cm away from lens, calculate image distance and magnification.

Answer 1

Everything is real, so everything is positive.

As u=30 & v=20 given

Put the formula of focal lenth

1/f = 1/u+1/v

1/f = 1/30 + 1/20

1/f = 2 + 3 /60

1/f = 5/60

1/ f = 12cm

F= 12 cm

Hope so its clear to u