Question

An electron at rest is accelerated by a potential $V_1$ and it experiences a force ‘F’ in a uniform magnetc field.When it is accelerated by a potential $V_2$ the electron experiences a force 2F in the same field. The value of $\frac{V_1}{V_2}$ is

• A. $\frac{1}{2}$
• B. $\frac{1}{4}$
• C. 2
• D. 4

Answer 1

The correct option is B $\frac{1}{4}$

$F=Bq\sqrt{\frac{2Vq}{m}}V\alpha F^2\frac{V_1}{V_2}={\left(\frac{F_1}{F_2}\right)}^2={\left[\frac{F}{2F}\right]}^2=\frac{1}{4}$