KCET 2020 Physics Solved Paper

The magnetic field due to a long straight current carrying wire is given by
B=

µ0I

2πr

or, B∝

1

r

At the point exactly mid-way between the conductors, the net magnetic field is zero. Using right hand thumb rule, we find that the magnetic field due to left wire will be in

^

j

direction while due to the right wire is in (−

^

j

) direction.
Magnetic field at a distance x from the left wire, lying between the wires.
B=

µ0I

2πx

^

j

+

µ0I

2π(2d−x)

(−

^

j

)
or, B=

µ0I

2π

(

1

x

−

1

2d−x

)
At x=d,B=0
For x<d,B is along

^

j

For x>d,B is along (−

^

j

)
On the left side of the left conductor, magnetic fields due to the currents will add up and the net magnetic field will be along(−

^

j

) direction.
To the right side of second conductor, the total magnetic field will be along

^

j

direction.