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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
Solution
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.
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