What is the solid angle subtended by the hemisphere at centre? 4π steradian 2π steradian π steradian 3π steradian

The solid angle subtended by a hemisphere at its center is 2π steradians.

Here's the step by step explanation:

1. A solid angle measures the amount of the field of view from some particular point that a given object covers. It is measured in steradians.

2. For a full sphere, the solid angle at the center is 4π steradians. This is because a sphere has 360 degrees of freedom, and when this is converted into radians (since 1 radian = 180/π degrees), we get 4π steradians.

3. However, a hemisphere is just half of a sphere. Therefore, the solid angle it subtends at its center is half of that of a full sphere.

4. Hence, the solid angle subtended by a hemisphere at its center is 2π steradians.