question_answer

A simple pendulum has time period T. The bob is given negative charge and surface below it is given positive charge. The new time period will be      [AFMC 2004]

A)            Less than T                            

B)            Greater than T

C)            Equal to T                              

D)            Infinite

Correct Answer: A

Solution :

                   In this case time period of pendulum becomes                    \[{T}'=2\pi \sqrt{\frac{l}{\left( g+\frac{qE}{m} \right)}}\]            Þ \[{T}'<T\]