Question

Plane angle and solid angle have –

• A. both units and dimensions
• B. units but no dimensions
• C. dimensions but no units
• D. no units \& no dimensions

Hint:

Plane and solid angles are assigned units (radian and steradian) but are dimensionless since they represent ratios of like quantities.

Answer 1

The Correct Option is B

Plane angle and solid angle are considered dimensionless physical quantities in the SI system.
However, they do possess units — the radian (rad) for plane angle and steradian (sr) for solid angle.
Since these quantities represent ratios (arc length to radius for plane angle and area to radius squared for solid angle), they have no physical dimensions, even though they are assigned standard units.