The magnetic field at a distance of $2 \mathrm {~cm}$ from a long straight current-carrying wire is $4 \mu T$. What is the magnetic field at a distance of $4 \mathrm {~cm}$ from this wire?
A) $6 \mu \mathrm { T }$
B) $4 \mu \mathrm { T }$
C) $10 \mu \mathrm { T }$
D) $2 \mu \mathrm { T }$
E) $8 \mu T$

Question

Quizplus · Accepted Answer

The magnetic field around a long straight current-carrying wire is inversely proportional to the distance from the wire. Therefore, if the distance is doubled, the magnetic field is halved. So, at 4 cm, the magnetic field is $2 \mu T$.

The Magnetic Field at a Distance Of 2 cm2 \mathrm {~cm}2 cm From a Long Straight Current-Carrying Wire Is

The Magnetic Field at a Distance Of $2 \mathrm {~cm}$ From a Long Straight Current-Carrying Wire Is