Rankers Physics

Magnetic Field Due to Straight Current Carrying Wire: Practice Problem & Solution

The magnetic field at a distance r from a long wire carrying current i is 0.4 tesla. The magnetic field at a distance 2r is (1992)
$0.2\text{ tesla}$
$0.8\text{ tesla}$
$0.1\text{ tesla}$
$1.6\text{ tesla}$

Solution Explained:

To solve this problem, we apply the core principles of Magnetic Field Due to Straight Current Carrying Wire. Understanding the underlying formula is key to arriving at the correct answer below:

Magnetic field due to a long straight wire is inversely proportional to distance ($B \propto 1/r$). When distance is doubled from $r$ to $2r$, the magnetic field is halved. Therefore, the new magnetic field is $0.4 / 2 = 0.2\text{ tesla}$.

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