A bob of mass $m$ is tied with a thread and is made to move in a circular path on a horizontal frictionless table about point $O$ as shown in the figure. A hypothetical electric field exists in the radial direction along the surface of the table. In this condition, the bob is uncharged and the tension in the thread is $T$. If now the bob is given some charge, then

• A

  Tension in thread must increase
• Correct answer
  B

  Tension in thread may increase or decrease
• C

  Tension in thread will remain unchanged
• D

  Tension in thread must decrease

Solution

Tension may increase or decrease depending on the nature of charge given to sphere.

Hence, the correct answer is option: 'B'.