Chapter 13 - Vibrations and Waves - Learning Path Questions and Exercises - Multiple Choice Questions - Page 482: 3

(b) halved

Recall the relation f= 1/T or T= 1/f. Given that the frequency is doubled. Let the new frequency be 2f then. We have, 2f= $\frac{1}{T}$ Rearranging the equation, We get, T= $\frac{1}{2f}$ = $\frac{1}{2}×\frac{1}{f}$. Clearly, the period is halved in this case.