Question

Which of the following graphs represent the variation of magnetic field \( B \) with perpendicular distance \( r \) from an infinitely long, straight conductor carrying current? 

• A.
• B.
• C.
• D.

Hint:

The magnetic field around a long straight conductor is inversely proportional to the distance from the conductor. This is a characteristic of magnetic fields around wires carrying current.

Answer 1

The Correct Option is C

For a long straight conductor carrying a current, the magnetic field at a distance \( r \) from the conductor is given by Ampere's Law: \[ B = \frac{\mu_0 I}{2 \pi r} \] This shows that the magnetic field is inversely proportional to the distance \( r \) from the conductor. As the distance increases, the magnetic field decreases, following a hyperbolic curve, as shown in option (3).
Thus, the correct graph is (3).