NEET2008PhysicsRay OpticsActual
A boy is trying to start a fire by focusing Sunlight on a piece of paper using an equiconvex lens of focal length 10 ~cm . The diameter of the Sun is 1.39 10^9 ~m and its mean distance from the earth is 1.5 10¹¹ ~m . What is the diameter of the Sun's image on the paper?
Options
- A12.4 10⁻⁴ ~m
- B9.2 10⁻⁴ ~m
- C6.5 10⁻⁴ ~m
- D6.5 10⁻⁵ ~m
Correct answer
B. 9.2 10⁻⁴ ~m
Step-by-step solution
Here, D / 2 u = d / 2 f aligned d & = D f u & = 1.39 10^8 10 10⁻² 1.5 10¹¹ =9.2 10⁻⁴ ~m aligned