The electron gun in a television tube accelerates electrons (mass = 9.11x10^-31 kg, charge = 1.6 x 10^-19C) from rest to 3 x10^7 m/s within a distance o 2 cm. What electric field is required?

Respuesta :

Answer:

Electric field acting on the electron is  127500 N/C.

Explanation:

It is given that,

Mass of an electron, [tex]m=9.11\times 10^{-31}\ kg[/tex]

Charge on electron, [tex]q=1.6\times 10^{-19}\ C[/tex]

Initial speed of electron, u = 0

Final speed of electron, [tex]v=3\times 10^7\ m/s[/tex]

Distance covered, s = 2 cm = 0.02 m

We need to find the electric field required. Firstly, we will find the acceleration of the electron from third equation of motion as :

[tex]a=\dfrac{v^2-u^2}{2s}[/tex]

[tex]a=\dfrac{(3\times 10^7)^2-0}{2\times 0.02}[/tex]

[tex]a=2.25\times 10^{16}\ m/s^2[/tex]

According to Newton's law, force acting on the electron is given by :

F = ma

[tex]F=9.1\times 10^{-31}\times 2.25\times 10^{16}[/tex]

[tex]F=2.04\times 10^{-14}\ N[/tex]

Electric force is given by :

F = q E, E = electric field

[tex]E=\dfrac{F}{q}[/tex]

[tex]E=\dfrac{2.04\times 10^{-14}}{1.6\times 10^{-19}}[/tex]

E = 127500 N/C

So, the electric field is 127500 N/C. Hence, this is the required solution.