A solenoid length 0.4cm, radius 1 cm and 400 turns of wire. If a current of 5 A is passed through this solenoid, what is the magnetic field inside the solenoid ?

Options

A. `6.28xx10^(-7)T`
B. `6.28xx10^(-4)T`
C. `6.28xx10^(-6)T`
D. `6.28xx10^(-3)T`

Explanation

Here,
Length, `l=0.4cm = 0.4 xx 10^(-2)m`
Radius, `r=1cm = 10^(-2)m`
Number of turns, `N=400`
Current, `I=5A`
Number of turns per unit length is
`n=N/l = (400)/(0.4xx10^(-2))=10^(5)` turns/m
Magnetic field inside the solenoid is
`B=mu_(0)n I = 4 pi xx 10^(-7)xx10^(5)xx5`
`=62.8xx10^(-2)T= 6.28xx10^(-1)T`
`**` None of the given options is correct.