A charged particle is whirled on a horizontal flat table by attaching it to a string fixed at one point. If a magnetic field is switched on in the vertical direction, the tension in the string

$\begin {array} {1 1} (a)\;Increases & \quad (b)\;Decreases \\ (c)\;May\: increase\: or \: decrease & \quad (d)\;Remains \: constant \end {array}$

The answer depends on the sign of the charge and the sense of rotation
Ans : (c)