Question

an object 50 cm tall is placed on the principal axis of a convex lens its 20 CM tall image is formed on the screen placed at a distance of 10cm from the lens calculate the object distance​

Answer 1

Answer:

v = 10 cm

h' = - 20 cm

h = 50 cm

m = v/u = h'/h

10/u = - 20/50

u = 50 X 10/-20 = 500/-20 = -25 cm

Lens formula :

1/v -1/u =1/f

1/10 - 1/-25 = 1/f

1/10 + 1/25 = 1/f

35/250 =7/50

f = 50/7 = 7.14 cm