The magnetic field at a certain distance from a wire carrying 2-A current is 4 μT. What will be the magnetic field if the current in the wire is doubled?
A) 2 μT
B) 4 μT
C) 6 μT
D) 8 μT
E) 10 μT

Question

Quizplus · Accepted Answer

The magnetic field produced by a wire carrying a current is directly proportional to the current flowing through it. Therefore, if the current is doubled, the magnetic field will also double.
So, if the initial current is 2 A and the magnetic field is 4 μT, the new magnetic field when the current is doubled to 4 A will be:
B = (μ0 I) / (2πr)
B' = (μ0 x 4A) / (2πr)
B' = 2 x (μ0 x 2A) / (2πr)
B' = 2 x B
B' = 2 x 4μT = 8μT.
Therefore, the correct answer is D) 8μT.

The Magnetic Field at a Certain Distance from a Wire