A section of the sphere cut by a plane through any of its great circles is a hemisphere. In another way, we can say, one half of a sphere is called a hemisphere.
Volume of a hemisphere:
Let \(r\) be the radius of a sphere.
Volume of a hemisphere \(=\) \(\times\) Volume of a sphere
Volume of a hemisphere \(=\) cu. units
Volume of hollow hemisphere (volume of the material used):
Let \(r\) be the inner radius and \(R\) be the outer radius of the hollow hemisphere.
Volume of hollow hemisphere \(=\) Volume of the outer hemisphere \(-\) Volume of the inner hemisphere
Volume of a hollow hemisphere \(=\) cu. units
The value of \(\pi\) should be taken as unless its value is shared in the problem.