Question

if energy of an electron is728 electron volt then obtain its velicity​

Answer 1

Answer:

Velocity of an electron, v = 1.6 x $10^{7}$ m/s

Explanation:

Given that

The energy of an electron = 728 eV

This electron volts need to be converted to joule. As per question, it accounts for the kinetic energy of an electron. It accounts for less than 10% mass energy (m$c^{2}$). So, the relativistic effect is neglected.

One electron volt, 1 eV = 1.602 x $10^{-19}$  Joule

Therefore, the kinetic energy of the electron

                                   E$_{k}$ = 728 x 1.602 x $10^{-19}$

                                   E$_{k}$ = 1.166256 x $10^{-16}$ J

The kinetic energy is given by the expression

                                   K$_{e}$ = 1/2 m$v^{2}$

Therefore, the velocity

                                    v =  $\sqrt{2E_{k}/m }$

where 'm' is the mass of electron

                                    m = 9.10938356 x $10^{-16}$ Kg

Substituting the above values

                                    v =  $\sqrt{\frac{2*1.166256 * 10^{-16}}{9.10938356 *10^{-31}} }$

                                       = 1.6 x $10^{7}$  m/s

So, the velocity of an electron v = 1.6 x $10^{7}$ m/s