Question

If the electric current through a copper wire increases, the magnitude of the magnetic field produced at a given point:

• A. decreases
• B. remains the same
• C. increases
• D. becomes equal to zero

Hint:

Magnetic field strength is directly proportional to the current producing it.

Answer 1

The Correct Option is C

Step 1: Recall the relationship between electric current and the magnetic field it produces.
A current-carrying wire produces a magnetic field around it. The magnitude of this magnetic field is directly proportional to the magnitude of the current flowing through the wire (Ampère's Law). Step 2: Consider Ampère's Law for a long straight wire.
The magnetic field ($B$) at a distance $r$ from a long straight wire carrying current $I$ is: \[ B = \frac{\mu_0 I}{2 \pi r} \] where \( \mu_0 \) is the permeability of free space. Step 3: Analyze the effect of increasing current.
From the formula, $B \propto I$. Thus, if the current $I$ increases, the magnetic field $B$ also increases at a given point ($r$ constant).