A long solenoid of 50 cm length having 100 turns carries a current of 2.5A. The magnetic field at centre of solenoid is:

Options

A. `6.28 xx 10^(-4) T`
B. `3.14 xx 10^(-4) T`
C. `6.28 xx 10^(-5) T`
D. `3.14 xx 10^(-5) T`

Answer

A

Explanation

Magnetic field at centre of solenoid = `mu_(0) nl`
`n =(N)/(L) = (100)/(50 xx 10^(-2)) = 200` turns/m
I = 2.5 A
`B = mu_(0) ""(N)/(L)"" I`
`= 4pi xx 10^(-7) xx (100)/((0.5)) xx 2.5`
`= 6.28 xx 10^(-4) T`