A helium nucleus makes a full rotation in a circle of radius 0.8 metre in two seconds. The value of the magnetic field B at the centre of the circle will be

Options

A. `(10^(-19))/(mu_(0))`
B. `10^(-19) mu_(0)`
C. `2 xx 10^(-10) mu_(0)`
D. `(2 xx 10^(-10))/(mu_(0))`

Answer

B

Explanation

Time period (T) = 2
`i=(q)/(T) = (2 xx 1.6 xx 10^(-19))/(2) = 1.6 xx 10^(-19) A`
Field at centre - `B = (mu_(0) I)/(2R) = (mu_0 xx 1.6 xx 10^(-19))/(2 xx 0.8) = mu_(0) xx 10^(-19) T`