A power line 8m high carries a current 100A. What is the magnetic field of wire at ground?
Correct answer: B. 2.5 x 10^-6 T
- A. 0.002 T
- B. 2.5 x 10^-6 T
- C. 0.005 T
- D. 4 x 10^-6 T
Explanation
The magnetic field at ground due to a current-carrying wire is given by the formula:B = μ₀I/(2πr)where μ₀ is the permeability of free space, I is the current, and r is the distance from the wire. Here, the current I = 100A and the distance from the wire r = 8m.Plugging these values into the formula, we get:B = (4π x 10^-7 Tm/A) x 100A / (2π x 8m)B = 2.5 x 10-6 TTherefore, the magnetic field at ground is 2.5 x 10-6 T.
This question appeared on the NUMS 2019 (cancelled sitting) paper, which you can sit online with every answer explained.
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About Magnetic Flux Density
Magnetic flux density measures the magnetic force acting on a current carrying conductor or moving charge in a magnetic field. Work includes the relations B equals F divided by IL and F equals qvB, the tesla as its SI unit, field direction and the distinction between flux density and magnetic flux.
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