Q

After passing through a concave lens, a beam appears to diverge from a point 25 cm behind the lens. What is the lens power?

RRB Group-D 06/10/2022 / Shift-I 2022
✓ Answer: D -4 D
The source treats the point as the virtual focus, with f = -25 cm, giving P = -4 D. For a concave lens with parallel input, the virtual focus is on the incident side; 'behind' is imprecise.
← Previous Question Next Question →

📚 Related Questions — Light

1 Which statement about C. V. Raman is wrong? 2 A ray parallel to the principal axis strikes a concave mirror. After… 3 Why do the seven colors of sunlight emerge separately after passing through… 4 Splitting sunlight into the colours of a rainbow is called _____. 5 The speed of light is _____. 6 For a given colour and pair of media, light travels from a…