Question

The volume of a hollow cylinder of inner radius $r_2$, outer radius $r_1$ and height h is ______ .

• A. $\pi (r_1^2-r_2^2)$
• B. $\pi h(r_1^2-r_2^2)$
• C. $\pi h(r_1-r_2)$
• D. $\pi h(2r_1^2-r_2^2)$

Answer 1

The correct option is B $\pi h(r_1^2-r_2^2)$

In case of hollow cylinder, we measure two radius, one for inner circle and one for outer circle formed by the base of hollow cylinder.
Suppose, $r_1$ is the outer radius and $r_2$ is the inner radius of the given hollow cylinder with h as the height, then the volume of this cylinder can be written as $\pi h(r_1^2-r_2^2)$ .