Question

A convex lens of focal length 10 cm project 10 cm tall image on a screen at a distance of 50 cm from the lens. estimate the position and size of the object​

Answer 1

Answer:

Given, f = 10cm , h' = -10cm , v = 50cm

So, by lense formula,

1/f = 1/v - 1/u

1/10 = 1/50 - 1/u

1/u = 1/50 - 1/10

1/u = -4/50

u = -12.5 cm

Now, by magnification formula,

v/u = h'/h

-50/12.5 = -10/h

h = 10×12.5/50

h = 125/50

h = 2.5 cm

Hence the object is 12.5 cm away from the lense and is 2.5 cm tall in size.