Question

When an electron is accelerated through a potential differences v, it experiences a force f through a uniform transverse magnetic field. if the potential difference is increased to 2v, the force experienced by the electron in the same magnetic field is?

Answer 1

Kinetic energy of an electron after passing through potential difference of V volt is given as

$\frac{1}{2}m v^{2}=eV$  

, m is the mass of the electron, while v is the velocity of the electron, e is the charge of electron and V is the voltage.

So,  

force is given as:

F= e v B

Substituting the value of v from the above equation:

$F1=e\times \sqrt{2e\frac{V}{m}}\times B$

So, if V is changed by 2V, then force will be F₂ that is  

$F_{2}=\sqrt{2F_{1}}$