NEET Magnetic Field Due to Straight Current Carrying Wire MCQs & PYQs

Practice NEET Magnetic Field Due to Straight Current Carrying Wire Questions

Question 1:

moderate

Given below are two statements

Statement I : Biot-Savart’s law gives us the expression for the magnetic field strength of an infinitesimal current element ($I d \vec{l}$) of the current carrying conductor only.

Statement II : Biot-Savart’s law is analogous to Coulomb’s inverse square law of charge $q$, with the former being related to the field produced by a scalar source, $Id \vec{l}$, while the latter being produced by a vector source, $q$.

In light of above statements choose the most appropriate answer from the options given below

Statement I is correct as Biot-Savart's law defines the magnetic field for a current element $I d \vec{l}$. Statement II is incorrect because $I d \vec{l}$ is a vector source while charge $q$ is a scalar source, reversing the description.

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Question 2:

easy

Tesla is the unit of

(1997, 88)

The SI unit of magnetic field (magnetic induction) is Tesla ($ \text{T} $), defined as one Weber per square meter ($ \text{Wb/m}^2 $).

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Question 3:

easy

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)

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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Question 4:

moderate

A long straight wire of radius $a$ carries a steady current $I$. The current is uniformly distributed over its cross-section. The ratio of the magnetic fields $B$ and $B’$ at radial distances $\frac{a}{2}$ and $2a$ respectively, from the axis of the wire is:

(2016-1)

The magnetic field inside the wire at distance $r = a/2$ is given by $B = \frac{\mu_0 I r}{2\pi a^2}$. The magnetic field outside at $r' = 2a$ is $B' = \frac{\mu_0 I}{2\pi r'}$. Evaluating both gives equal magnitudes, so the ratio $B / B'$ is equal to $1$.

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