A charge of `(3.14 xx 10^-6)` C is distributed uniformly over a circular ring of radius 20.0 cm. The ring rotates about its axis with an angular velocity of 60.0 `rad s^(-1)` . Find the ratio of the electric field to the magnetic field at a point on the axis at a distance of 5.00 cm from the centre.

Explanation

Current due to rotation of charge
`i=Q/T=Q/(2pi//omega)=(Qomega)/(2pi)`
At `P:`
`E=1/(4pi epsilon_(0)) (Qx)/((R^(2)+x^(2))^(3//2))`
`B=(mu_(0)iR^(2))/(2(R^(2)+x^(2))^(3//2))=(mu_(0)QomegaR^(2))/(4pi(R^(2)+x^(2))^(3//2))`
`E/B=1/(mu_(0)epsilon_(0)). x/(omegaR^(2))`
`=(c^(2)(R//4))/(omegaR^(4)).c:` speed of light
`=(c^(2))/(4 omegaR)=((3xx10^(8))^(2))/(4xx60xx0.2)=(9xx10^(16))/48`
`=1.88xx10^(15) m//sec`