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

Answer:

Zero

Explanation:

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

$B_1=\dfrac{\mu_oI_1}{2\pi r}$

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

$F_{2}=I_2lB_1$

$F_2=\dfrac{\mu_oI_1I_2 l}{2\pi r}$

Similarly, force acting in wire 1 is given by :

$F_1=\dfrac{\mu_oI_1I_2 l}{2\pi r}$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.