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Question
A horizontal overhead power line carries a current of 90 A in east to west direction. What is the magnitude and direction of the magnetic field due to the current 1.5 m below the line?
Solution
Current in the power line, I = 90 A
Point is located below the power line at distance, r = 1.5 m
Hence, magnetic field at that point is given by the relation,
B =
Where,
μ0 = Permeability of free space = 4π × 10–7 T m A–1
B =
= 1.2 × 10–5 T
The current is flowing from East to West. The point is below the power line. Hence, according to Maxwell’s right-hand thumb rule, the direction of the magnetic field is towards the South.
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