Question

Uploaded imageTwo long, parallel wires each carry the same current I in the same direction (see figure below). The total magnetic field at the point P midway between the wires is in what direction?

a.zero
b.directed into the page
c.directed out of the page
d.directed to the left
e.directed to the right

Answer 1

Zero

Step-by-step explanation:

Two long parallel wires each carry the same current I in the same direction. The magnetic field in wire 1 is given by :

`B_1=(\mu_oI_1)/(2\pi r)`

Magnetic force acting in wire 2 due to 1 is given by :

`F_(2)=I_2lB_1`

`F_2=(\mu_oI_1I_2 l)/(2\pi r)`

Similarly, force acting in wire 1 is given by :

`F_1=(\mu_oI_1I_2 l)/(2\pi r)`According to third law of motion, the force acting in wire 1 will be in opposite direction to wire 2 as :

`F_2=-F_1`

So, the total magnetic field at the point P midway between the wires is in what direction will be zero as the the direction of forces are in opposite direction.