Magnetic moment of a bar magnet is 2.4 `Am^(2)`A point is situated at 20 cn from its centre on a line making an angle of `30^(@)`with axis.The magnetic induction at that point is

Options

A. `5.42xx10^(-5) Wb//m^(2)`
B. `5.14xx10^(-5) Wb//m^(2)`
C. `4.51xx10^(-5)Wb//m^(2)`
D. `4.15xx10^(-5)Wb//m^(2)`

Answer

A

Explanation

`B=mu_(0)/(4pi)(M)/(r^(3))sqrt(3cos^(2)theta+1)`
`(4pixx10^(-7)xx2.4)/(4pixx(0.2)^(3))sqrt(3cos^(2)30+1)`
`~~5.41xx10^(-5)Wb//m^(2)`