Question

. In a television picture tube, electrons strike the screen after being accelerated from rest through a potential difference of 22000 V. The speeds of the electrons are quite large, and for accurate calculations of the speeds, the effects of special relativity must be taken into account. Ignoring such effects, find the electron speed just before the electron strikes the screen.

Answer 1

Answer:

The speeds of the electrons is $8.79\times10^{7}\ m/s$

Explanation:

Given that,

Potential difference = 22000 V

The difference in electron potential energy is converted  into kinetic energy.

We need to calculate the speed

Using conservation of energy

$K.E=\Delta EPE$

$\dfrac{1}{2}mv^2=q\Delta V$

$v=\sqrt{\dfrac{2q\Delta V}{m}}$

Where, V = potential difference

q = charge of electron

m = mass of electron

$v=\sqrt{\dfrac{2\times1.6\times10^{-19}\times22000}{9.1\times10^{-31}}}$

$v=8.79\times10^{7}\ m/s$

Hence, The speeds of the electrons is $8.79\times10^{7}\ m/s$