A particle of mass m is attached to a string and is moving in a vertical circle. Tension in the string when the particle is at highest and lowest point is $T_1$ and $T_2$ respectively.Here $T_1 - T_2$ is equal to

3 mg 4 mg 5 mg 6 mg

4 mg

Tension at the highest point is $T_1$ = 5mg Tension at the lowest point is $T_2$ = mg Then $T_1 - T_2$ = 4 mg