Question

An opaque cylinder (shown below) is suspended in the path of a parallel beam of light, such that its shadow is cast on a screen oriented perpendicular to the direction of the light beam. The cylinder can be reoriented in any direction within the light beam. Under these conditions, which one of the shadows P, Q, R, and S is NOT possible?

• A. P
• B. Q
• C. R
• D. S

Hint:

Shadows of cylindrical objects can be circular or elliptical depending on the angle of light. Unusual or impossible shadows result from incorrect assumptions about the object's positioning or light angles.

Answer 1

The Correct Option is D

We are given an opaque cylinder suspended in the path of a parallel beam of light, and the task is to analyze which shadow cannot be formed based on the cylinder's reorientation.
1) Shadow Formation:
When a cylindrical object is in the path of light, the shadow produced depends on the orientation of the cylinder.
When the cylinder is oriented with its axis perpendicular to the direction of the light, it will cast a circular shadow.
When the cylinder is reoriented with its axis at an angle to the light, the shadow may become elliptical.
A shadow like \( S \) (which appears highly distorted) is not physically possible as it would require an impossible angle or distortion of light.
2) Conclusion:
The shadow in option \( S \) cannot be produced by the cylinder under the given conditions. Therefore, the correct answer is option (D).
The correct answer is (D) S.