Question

what is the object distance if power is -2.5:D and image distance is -10 cm ? please solve it....​

Answer 1

GIVEN:

V= -10 Cm

P= -2.5 D

U= ???

Explanation:

P= 1/f

f= 1/P

f= 1/(-2.5)

f= -0.4 m

f= -40 cm

the question was for Lens,

1/f= 1/v - 1/u

1/u = 1/v - 1/f

1/u = 1/(-10) - 1/(-40)

= 1/(-10) + 1/40

= 4/(-40) + 1/40

= 4+1/-40

= 5/-40

u = -40/5

U = -80 Cm.