# The bob of a pendulum of mass $100\;g$ is at equilibrium in a horizontal uniform electric field of $2.5 \times 10^5 V m^{−1}$. In this equilibrium position, the pendulum makes an angle with the vertical. The amount of charge on the bob is $3 \mu C$. Assume that the bob is suspended by means of a thin mass-less string. What is the tension in the string when the bob is at equilibrium?

$1.23 \;N$ is correct.