Question

Consider the following statements about the Oersted experiment.

Statement $\text{P}:$ The magnetic field due to a straight current carrying conductor is in the form of circular loops around it.

Statement $\text{Q}:$The magnetic field due to a current carrying conductor is strong at far points from the conductor, compared to the near points.

• A. Both $\text{P}$ and $\text{Q}$ are true
• B. $\text{P}$ is true but $\text{Q}$ is false
• C. $\text{P}$ is false but $\text{Q}$ is true
• D. Both $\text{P}$ and $\text{Q}$ are false

Answer 1

The correct option is B $\text{P}$ is true but $\text{Q}$ is false

From the experiment, the diagrams show the magnetic field pattern around a straight conductor carrying current.


The magnetic field lines around a straight conductor carrying current are concentric circles whose centres lie on the wire.

According to Biot- Savart Law,

$dB=\frac{{\mu }_0}{4\pi }\frac{idl\sin \theta }{r^2}$

$\Rightarrow dB\propto \frac{1}{r^2}$

Therefore, the magnetic field at the near points will be more compared to the far points.

Hence, option $\left(B\right)$ is the correct answer.