An electorn moves in a circle of radius 10cm with a constant speed of `4.0xx10^(6)ms^(-1)`.Find the electric current at a point on the circle.

Explanation

consider a point A on the circle. The electron crosses this point once in every revolution.In one revolution, the electron travels travels `2(pi)xx(10cm)`distance. Hence, number of revolution made by the electron in one second is
`(4.0xx10^(6)m)/(20(pi)xx(10^(-2)m)=(2)/(pi)x10^(7).`
the charge crossing the point A per second is` (2)/(pi)xx10^(7)xx1.6xx10^(-19)C=3.2/(pi)xx10^(-12)C`.thus the electric current at this point is
`3.2/(pi)xx10^(-12)A~~1.0xx10^(-12)A.`