Question

1.An electron has an energy of 2.3 ev. What is the energy of the electronic in J?

2.The shopping potential for a photoelectric cell is 5.7 v. Calculate the maximum kinetic energy of the emitted photo electrons in ev?

3.What is the energy in ev of an electron with a velocity of 6.2×10 6m/s

Answer 1

1.

$$\rm 2.3\: eV=2.3*1.6*10^{-19}\: J=3.68*10^{-19}\: J$$

2.

$$E_{k\max}=eV=5.7\:\rm eV$$

3.

$$E_k=\frac{mv^2}{2}\\ =\frac{9.1*10^{-31}*(6.2*10^6)^2}{2}\div1.6*10^{-19}=109\: \rm eV$$