What must be the distance between an object and a converging lens of focal length 20cm to produce an erect image two times the object height?
- 20cm
- 15cm
-
10cm
- 5cm
The correct answer is: C
Explanation
F = \(\frac{uv}{u + v}\); v = 2u20 = \(\frac{ux - 2u}{u + (-2u)}\); u = 10cm