# An electron is rotating around an infinite positive linear charge in a circle of radius of 0.1 m , if linear charge density is 1 micro coulomb per meter, then velocity of electron in m/s is? . . . . . pls help as soon as possible

18 Points
14 years ago

Hi mohmmed

You can imagine the postive linear charge as vertical rod and electron moving around it in a circle horizontaly.

the image uploaded might help in visualization.

Now you know that there will be a force of attraction among the opposite charges and also since electron is revolving in a circle ,there will be a centrifugal force(repulsive) acting on it.

These forces will be equal and opposite and thus will form the equation.

electrostatic force will be, F1 = qE (where q is electron,1.6*10^-19 and E is electric field due to infinte linear charge )

E = λ (per unit charge) =   1.7974*10^4

2 ∏ ε

and centrifugal force, F2 will be fiven by = mass * velocity^2  / radius

mass of electron : 9.1 * 10^-31

equating these two forces , we get v = 1.78 * 10^8   .