Question

What is the unit of measurement of solid angles?

• A. Steradian
• B. Degrees
• C. Radians
• D. Grades

Hint:

The unit for measuring solid angles is steradian (sr), which is the standard SI unit.

Answer 1

The Correct Option is A

Step 1: Understand the concept of a solid angle.
A solid angle is a measure of the two-dimensional angle in three-dimensional space that an object subtends at a point.
It is analogous to a plane angle, which is a two-dimensional angle.
Step 2: Know the formula for solid angle.
The formula for a solid angle \( \Omega \) is given by: \[ \Omega = \frac{A}{r^2} \] where \( A \) is the area subtended by the object and \( r \) is the distance from the point to the object.

Step 3: Unit of solid angle.
The unit of solid angle is the steradian (sr), which is defined as the solid angle subtended at the center of a sphere by an area equal to the square of the radius of the sphere.