Question

A hollow cylinder is lit by sunlight at 45 degrees as shown on the left. If seen from a fixed point, which option is the closest representation of the lit area inside the cylinder?

• A. Fig A
• B. Fig B
• C. Fig C
• D. Fig D

Hint:

Projecting a circle onto a concentric cylindrical surface always yields smooth, continuous curved boundaries. Avoid options with sharp, angular corners on the cylinder walls.

Answer 1

The Correct Option is A

Step 1: Trace the rays.
Parallel light at 45 degrees lights one side of the inner wall in an elliptical patch.
Step 2: View the lit zone.
Unrolled, the shadow edge is sinusoidal; from the given viewpoint it matches Fig A.
\[ \boxed{\text{Option 1 (Fig A)}} \]