Question

. An electron is accelerated through 2 400 V from rest and then enters a uniform 1.70-T magnetic field. What are (a) the maximum and (b) the minimum values of the magnetic force this particle can experience? 

Answer 1

a)

$$qU=0.5mv^2\\v=\sqrt{\frac{2qU}{m}}\\F=qvB \\F=qB\sqrt{\frac{2qU}{m}}\\F=(1.6\cdot10^{-19})(1.7)\sqrt{\frac{2(2400)(1.6\cdot10^{-19})}{(9.1\cdot10^{-31})}}\\=7.9\cdot10^{-12}\ N$$

b) If the magnetic field is parallel to the motion of the electron:

$$F=0\ N$$