How does the doubling of a radius affect the circumference?

Doubling the radius of a circle results in the circumference also doubling. The circumference ( C ) of a circle is calculated using the formula ( C = 2\pi r ), where ( r ) is the radius. Therefore, if the radius is increased from ( r ) to ( 2r ), the new circumference becomes ( C = 2\pi(2r) = 4\pi r ), which is exactly twice the original circumference.