Two long thin wires ABC and DEF are arranged as shown in the figure. They carry currents I. The magnitude of the magnetic field at O is

Options

A. zero
B. `(mu_(0)I)/(4pia)`
C. `(mu_(0)I)/(2pia)`
D. `(mu_(0)I)/(sqrt2pia)`

Answer

C

Explanation

Section AB and DE produce no field at O.Section BC and EF produce equal filds atO,each `=(mu_(0)I)/((4pia))`.
The magnetic of magnetic field at O is `B=B_(BA)+B_(BC)+B_(DE)+B_(EF)`
`=0+(mu_(0)I)/(4pia)+0+(mu_(0)I)/(4pia)=(mu_(0)I)/(2pia)`