A circular coil of diameter 21 cm is placed in a magnetic field of induction `10^(-4)`T. the magnitude of flux linked with coil when the plane of coil makes an angle `30^(@)` with the field is

Options

A. `1.44xx10^(-6)Wb`
B. `1.732xx10^(-6)Wb`
C. `3.1xx10^(-6)Wb`
D. `4.2xx10^(-6)Wb`

Answer

B

Explanation

Magnetic flux, `phi=B.A=BA costheta`, where `theta` is an angle
between normal to the area A and magnetic field B.
Here, `theta=(90^(@)-30^(@))=60^(@)`
and `phi=10^(-4)xxpi((21)/(2)xx10^(-2))^(2)xxcos60^(@)(because A=pir^(2))`
`=1.732xx10^(-6)Wb`