Question

Two horizontal thin long parallel wires, separated by a distance r carry current I each in the opposite directions. The net magnetic field at a point midway between them will be ______.

Options

• zero

• `((mu_0I)/(2pir))` vertically downward

• `((2mu_0I)/r)` vertically upward

• `((mu_0I)/(pir))` vertically downward

Answer 1

Two horizontal thin long parallel wires, separated by a distance r carry current I each in the opposite directions. The net magnetic field at a point midway between them will be zero.

Explanation:

When the right-hand thumb points in the direction of the current-carrying conductor, the fingers curl in the direction of the magnetic field around the current-carrying conductor, according to the thumb rule. As a result, the magnetic field at the spot caused by the wire on the left is pointing downwards. Using the same idea, the magnetic field at the place due to the right-hand side wire exists downwards. As a result, after adding the two magnetic fields, the net field is zero.