Electromagnetism PYQ — Page 24

The $H$ amount of thermal energy is developed by a resistor in $10s$ when a current of $4A$ is passed through it. If the current is increased to $16A$, the thermal energy developed by the resistor in $10s$ will be

In an LC oscillator, if values of inductance and capacitance become twice and eight times, respectively, then the resonant frequency of oscillator becomes $x$ times its initial resonant frequency ${\omega }_{0}$. The value of $x$ is:

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 $600\Omega$, the voltmeter with resistance $1000\Omega$ will be preferred over voltmeter with resistance $4000\Omega$. 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

An electron is moving along the positive x-axis. If uniform magnetic field is applied parallel to the negative z-axis, then A.The electron will experience magnetic force along positive y-axis B.The electron will experience magnetic force along negative y-axis C.The electron will not experience any force in magnetic field D.The electron will continue to move along the positive x-axis E.The electron will move along circular path in magnetic field Choose the correct answer from the option given below:

A single turn current loop in the shape of a right angle triangle with sides $5\mathrm{cm},12\mathrm{cm},13\mathrm{cm}$ is carrying a current of $2A$. The loop is in a uniform magnetic field of magnitude $0.75T$ whose direction is parallel to the current in the $13\mathrm{cm}$ side of the loop. The magnitude of the magnetic force on the $5\mathrm{cm}$ side will be $\frac{x}{130}N$. The value of $x$ is _______.

In this figure the resistance of the coil of galvanometer $G$ is $2Ω$. The emf of the cell is $4V$. The ratio of potential difference across ${C}_{1}$ and ${C}_{2}$ is 

The electric field at a distance r from an infinitely long uniformly charged wire having linear charge density λ is:

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : If an electric dipole of dipole moment $30\times {10}^{–5}Cm$ is enclosed by a closed surface, the net flux coming out of the surface will be zero. Reason R : Electric dipole consists of two equal and opposite charges. In the light of above, statements, choose the correct answer from the options given below.

A capacitor of capacitance $C$ is charged to a potential $V$. The flux of the electric field through a closed surface enclosing the positive plate of the capacitor is:

Two cells are connected between points $A$ and $B$ as shown. Cell 1 has emf of $12V$ and internal resistance of $3\Omega$. Cell 2 has emf of $6V$ and internal resistance of $6\Omega$. An external resistor $R$ of $4\Omega$ is connected across $A$ and $B$. The current flowing through $R$ will be ______ $A$. 

The drift velocity of electrons for a conductor connected in an electrical circuit is ${V}_{d}$. The conductor is now replaced by another conductor with same material and same length but double the area of cross-section. The applied voltage remains same. The new drift velocity of electrons will be

In the given circuit, $rms$ value of current $({I}_{rms})$ through the resistor $R$ is : 

A plane electromagnetic wave of frequency $20\mathrm{MHz}$ propagates in free space along $x$-direction. At a particular space and time $\vec{E}=6.6\hat{j}V{m}^{-1}$. What is $\vec{B}$ at this point?

As per the given figure, if $\frac{dI}{dt}=-1A{s}^{-1}$, then the value of ${V}_{\mathrm{AB}}$ at this instant will be ______ $V$. 

The ratio of magnetic field at the centre of a current carrying coil of radius $r$ to the magnetic field at distance $r$ from the centre of coil on its axis is $\sqrt{x}:1$. The value of $x$ is _____.

Equivalent resistance between the adjacent corners of a regular $n$-sided polygon of uniform wire of resistance $R$ would be :

For a charged spherical ball, electrostatic potential inside the ball varies with $r$ as $V=2a{r}^{2}+b$. Here, $a$ and $b$ are constant and $r$ is the distance from the center. The volume charge density inside the ball is $-\lambda a\epsilon$. The value of $\lambda$ is ______. $\epsilon =$ permittivity of medium.

Given below are two statements: Statement I: If the number of turns in the coil of a moving coil galvanometer is doubled then the current sensitivity becomes double. Statement II: Increasing current sensitivity of a moving coil galvanometer by only increasing the number of turns in the coil will also increase its voltage sensitivity in the same ratio In the light of the above statements, choose the correct answer from the options given below:

The equivalent resistance between $A$ and $B$ as shown in figure is: 

For a moving coil galvanometer, the deflection in the coil is $0.05\mathrm{rad}$ when a current of $10\mathrm{mA}$ is passed through it. If the torsional constant of suspension wire is $4.0\times {10}^{–5}Nm{\mathrm{rad}}^{-1}$, the magnetic field is $0.01T$ and the number of turns in the coil is $200$, the area of each turn (in ${\mathrm{cm}}^{2}$ ) is :

A hollow cylindrical conductor has length of $3.14m$, while its inner and outer diameters are $4\mathrm{mm}$ and $8\mathrm{mm}$ respectively. The resistance of the conductor is $n\times {10}^{-3}\Omega$. If the resistivity of the material is $2.4\times {10}^{-8}\Omega m$. The value of $n$ is _____.

Three point charges $q,-2q$ and $2q$ are placed on $x$ axis at a distance $x=0,x=\frac{3}{4}R$ and $x=R$ respectively from origin as shown. If $q=2\times {10}^{-6}C$ and $R=2\mathrm{cm}$, the magnitude of net force experienced by the charge $-2q$ is _____ $N$. 

A point charge $2\times {10}^{–2}C$ is moved from $P$ to $S$ in a uniform electric field of $30N{C}^{–1}$ directed along positive $x$-axis. If coordinates of $P$ and $S$ are $(1,2,0)m\text{and}(0,0,0)m$ respectively, the work done by electric field will be

Match List I and List II <table class="pyq-table"><tbody><tr><td>A</td><td>Gauss’s Law in Electrostatics</td><td>I</td><td>$\oint \vec{E}\cdot \vec{dl}=-\frac{d{\phi }_{B}}{dt}$</td></tr><tr><td>B</td><td>Faraday's Law</td><td>II</td><td>$\oint \vec{B}\cdot d\vec{A}=0$</td></tr><tr><td>C</td><td>Gauss’s Law in Magnetism</td><td>III</td><td>$\oint \vec{B}\cdot d\vec{l}={\mu }_{0}{i}_{c}+{\mu }_{0}{\in }_{0}\frac{d{\phi }_{E}}{dt}$</td></tr><tr><td>D</td><td>Ampere-Maxwell Law</td><td>IV</td><td>$\oint \vec{E}\cdot d\vec{s}=\frac{q}{{\in }_{0}}$</td></tr></tbody></table>Choose the correct answer from the options given below :