One ring of radius a is uniformly charged with charge +Q and is placed so its axis is the x-axis. A second ring with charge –Q is placed concentric with the first and in the same plane. The radius of this ring is a/2. If a = 1m and Q = 3µC, what force is exerted on an electron 5m to the right of these along their common axis?

Respuesta :

Answer:

The force exerted on an electron is [tex]7.2\times10^{-18}\ N[/tex]

Explanation:

Given that,

Charge = 3 μC

Radius a=1 m

Distance  = 5 m

We need to calculate the electric field at any point on the axis of a charged ring

Using formula of electric field

[tex]E=\dfrac{kqx}{(a^2+x^2)^{\frac{3}{2}}}\hat{x}[/tex]

[tex]E_{1}=\dfrac{kqx}{(a^2+x^2)^{\frac{3}{2}}}\hat{x}[/tex]

Put the value into the formula

[tex]E_{1}=\dfrac{9\times10^{9}\times3\times10^{-6}\times5}{(1^2+5^2)^{\frac{3}{2}}}[/tex]

[tex]E_{1}=1.0183\times10^{3}\ N/C[/tex]

Using formula of electric field again

[tex]E_{2}=\dfrac{kqx}{(a^2+x^2)^{\frac{3}{2}}}\hat{x}[/tex]

Put the value into the formula

[tex]E_{2}=\dfrac{9\times10^{9}\times(-3\times10^{-6})\times5}{((0.5)^2+5^2)^{\frac{3}{2}}}[/tex]

[tex]E_{2}=-1.064\times10^{3}\ N/C[/tex]

We need to calculate the resultant electric field

Using formula of electric field

[tex]E=E_{1}+E_{2}[/tex]

Put the value into the formula

[tex]E=1.0183\times10^{3}-1.064\times10^{3}[/tex]

[tex]E=-0.045\times10^{3}\ N/C[/tex]

We need to calculate the force exerted on an electron

Using formula of electric field

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

[tex]F=E\times q[/tex]

Put the value into the formula

[tex]F=-0.045\times10^{3}\times(-1.6\times10^{-19})[/tex]

[tex]F=7.2\times10^{-18}\ N[/tex]

Hence, The force exerted on an electron is [tex]7.2\times10^{-18}\ N[/tex]