Embibe Experts Solutions for Chapter: Magnetic Effects of Current and Magnetism, Exercise 1: JEE Main - 10th April 2019 Shift 2

A bar magnet with a magnetic moment $5.0 \mathrm{A} {\mathrm{m}}^2$ is placed in parallel position relative to a magnetic field of $0.4 \mathrm{T}$. The amount of required work done in turning the magnet form parallel to antiparallel position relative to the field direction is ________.

A rod with circular cross-section area $2 {\mathrm{cm}}^2$ and length $40 \mathrm{cm}$ is wound uniformly with $400$ turns of an insulated wire. If a current of $0.4 \mathrm{A}$ flows in the wire windings, the total magnetic flux produced inside windings is $4\mathrm{\pi }\times {10}^{-6} \mathrm{Wb}$. The relative permeability of the rod is

(Given : Permeability of vacuum ${\mathrm{\mu }}_0=4\mathrm{\pi }\times {10}^{-7} \mathrm{N} {\mathrm{A}}^{-2}$)

A long conducting wire having a current $I$ flowing through it, is bent into a circular coil of $N$ turns. Then it is bent into a circular coil of $n$ turns. The magnetic field is calculated at the centre of coils in both the cases. The ratio of the magnetic field in first case to that of second case is:

The number of turns of the coil of a moving coil galvanometer is increased in order to increase current sensitivity by $50\%$. The percentage change in voltage sensitivity of the galvanometer will be :

Find the magnetic field at the point P in figure. The curved portion is a semicircle connected to two long straight wires.

A charge particle of $2 \mathrm{\mu C}$ accelerated by a potential difference of $100 \mathrm{V}$ enters a region of uniform magnetic field of magnitude $4 \mathrm{mT}$ at right angle to the direction of field. The charge particle completes semicircle of radius $3 \mathrm{cm}$ inside magnetic field. The mass of the charge particle is ______ $\times {10}^{-18} \mathrm{kg}$.

As shown in the figure, a long straight conductor with semicircular arc of radius $\frac{\mathrm{\pi }}{10} m$ is carrying current $I = 3A$. The magnitude of the magnetic field. at the center $O$ of the arc is: (The permeability of the vacuum $= 4\mathrm{\pi }\times {10}^{-7}{\mathrm{NA}}^{-2}$ )

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R.

Assertion A : For measuring the potential difference across a resistance of $600 \mathrm{\Omega }$, the voltmeter with resistance $1000 \mathrm{\Omega }$ will be preferred over voltmeter with resistance $4000 \mathrm{\Omega }$.

Reason R : Voltmeter with higher resistance will draw smaller current than voltmeter with lower resistance.

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