A proton is shot perpendicularly at an infinite plane of charge. The charge density of the plane is +7.65×10^−4 C/m^2. If the proton starts out 1.05 mm from the plane, what must its velocity be so that it screeches to a halt exactly as it reaches the plane?

Respuesta :

Answer:

The velocity is [tex]2.94\times10^{6}\ m/s[/tex].

Explanation:

Given that,

Charge density of the plane [tex]\sigma=7.65\times10^{−4}\ C/m^2[/tex]

Distance = 1.05 mm

We need to calculate the electric field due to plane of charge

Using formula of electric field

[tex]E=\dfrac{\sigma}{2\epsilon}[/tex]

Put the value into the formula

[tex]E=\dfrac{7.65\times10^{−4}}{2\times8.85\times10^{-12}}[/tex]

[tex]E=4.322\times10^{7}\ N/C[/tex]

We need to calculate potential difference

Using formula of potential difference

[tex]V=E\times r[/tex]

Put the value into the formula

[tex]V=4.322\times10^{7}\times1.05\times10^{-3}[/tex]

[tex]V=4.5381\times10^{4}\ Volt[/tex]

We need to calculate the work requires to be done to reach the surface of the plane

Using formula of work done

[tex]W=qV[/tex]

Put the value into the formula

[tex]W = 1.6\times10^{-19}\times4.5381\times10^{4}[/tex]

[tex]W=7.26096\times10^{-15}\ J[/tex]

We need to calculate the velocity

Using work energy theorem

[tex]W=\dfrac{1}{2}mv^2[/tex]

[tex]v^2=\dfrac{2W}{m}[/tex]

[tex]v=\sqrt{\dfrac{2\times7.26096\times10^{-15}}{1.67\times10^{-27}}}[/tex]

[tex]v=2.94\times10^{6}\ m/s[/tex]

Hence, The velocity is [tex]2.94\times10^{6}\ m/s[/tex].