Electromagnetism PYQ — Page 26

$10$ resistors each of resistance $10Ω$ can be connected in such as to get maximum and minimum equivalent resistance. The ratio of maximum and minimum equivalent resistance will be________.

A cell of emf $90V$ is connected across series combination of two resistors each of $100\Omega$ resistance. A voltmeter of resistance $400\Omega$ is used to measure the potential difference across each resistor. The reading of the voltmeter will be:

Given below are two statements: Statement I : Out of microwaves, infrared rays and ultraviolet rays, ultraviolet rays are the most effective for the emission of electrons from a metallic surface Statement II : Above the threshold frequency, the maximum kinetic energy of photoelectrons is inversely proportional to the frequency of the incident light In the light of above statements, choose the correct answer from the options given below

In the network shown below, the charge accumulated in the capacitor in steady state will be: 

A coil has an inductance of $2H$ and resistance of $4\Omega$. A $10V$ is applied across the coil. The energy stored in the magnetic field after the current has built up to its equilibrium value will be _____ $\times {10}^{-2}J$

For the plane electromagnetic wave given by $E={E}_{0}\mathrm{sin}(\omega t–kx)$ and $B={B}_{0}\mathrm{sin}(\omega t-kx),$ the ratio of average electric energy density to average magnetic energy density is

The magnitude of magnetic induction at mid-point $O$ due to current arrangement as shown in figure will be .

A straight wire carrying a current of $14A$ is bent into a semicircular arc of radius $2.2\mathrm{cm}$ as shown in the figure. The magnetic field produced by the current at the centre $O$ of the arc is ____ $\times {10}^{–4}T$ 

Different combination of $3$ resistors of equal resistance $R$ are shown in the figures. The increasing order for power dissipation is: (A)  (B)  (C)  (D) 

A potential ${V}_{0}$ is applied across a uniform wire of resistance $R.$ The power dissipation is ${P}_{1}.$ The wire is then cut into two equal halves and a potential of ${V}_{0}$ is applied across the length of each half. The total power dissipation across two wires is ${P}_{2}.$ The ratio of ${P}_{2}:{P}_{1}$ is $\sqrt{x}:1.$ The value of $x$ is _____.

A square loop of side $2.0\mathrm{cm}$ is placed inside a long solenoid that has $50$ turns per centimetre and carries a sinusoidally varying current of amplitude $2.5A$ and angular frequency $700\mathrm{rad}{s}^{-1}$. The central axes of the loop and solenoid coincide. The amplitude of the emf induced in the loop is $x\times {10}^{-4}V$. The value of $x$ is ___________ $($ Take, $\pi =\frac{22}{7})$

A parallel plate capacitor with plate area $A$ and plate separation $d$ is filled with a dielectric material of dielectric constant $K=4.$ The thickness of the dielectric material is $x,$ where $x<d.$  Let ${C}_{1}$ and ${C}_{2}$ be the capacitance of the system for $x=\frac{1}{3}d$ and $x=\frac{2d}{3},$ respectively. If ${C}_{1}=2\mu F$, the value of ${C}_{2}$ is _____ $\mu F.$

Match the List-I with List-II. <table class="pyq-table"><tbody><tr><td></td><td>List I</td><td></td><td>List II</td></tr><tr><td>A</td><td>AC generator</td><td>I</td><td>Presence of both L and C</td></tr><tr><td>B</td><td>Transformer</td><td>II</td><td>Electromagnetic Induction</td></tr><tr><td>C</td><td>Resonance phenomenon to occur</td><td>III</td><td>Quality factor</td></tr><tr><td>D</td><td>Sharpness of resonance</td><td>IV</td><td>Mutual Inductance</td></tr></tbody></table>Choose the correct answer from the options given below:

A single current carrying loop of wire carrying current $I$ flowing in anticlockwise direction seen from $+vez$ direction and lying in $xy$ plane is shown in figure. The plot of $\hat{j}$ component of magnetic field $(By)$ at a distance $a$ (less than radius of the coil) and on $yz$ plane $vsz$ coordinate looks like 

Given below are two statements: Statement I: For diamagnetic substance $-1\leq x<0$, where $x$ is the magnetic susceptibility. Statement II: Diamagnetic substance when placed in an external magnetic field, tend to move from stronger to weaker part of the field. In the light of the above statements, choose the correct answer from the options give below.

A charge particle of $2\mu C$ accelerated by a potential difference of $100V$ 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 ______ $\times {10}^{-18}\mathrm{kg}$.

A parallel plate capacitor of capacitance $2F$ is charged to a potential $V$. The energy stored in the capacitor is ${E}_{1}$. The capacitor is now connected to another uncharged identical capacitor in parallel combination. The energy stored in the combination is ${E}_{2}$. The ratio $\frac{{E}_{2}}{{E}_{1}}$ is

Two long parallel wires carrying currents $8A$ and $15A$ in opposite directions are placed at a distance of $7\mathrm{cm}$ from each other. A point $P$ is at equidistant from both the wires such that the lines joining the point $P$ to the wires are perpendicular to each other. The magnitude of magnetic field at $P$ is ______ $\times {10}^{-6}T$. (Given: $\sqrt{2}=1.4$)

The current required to be passed through a solenoid of $15\mathrm{cm}$ length and $60$ turns in order to demagnetise a bar magnet of magnetic intensity $2.4\times {10}^{3}A{m}^{–1}$ is ________ $A$.

In an electromagnetic wave, at an instant and at a particular position, the electric field is along the negative z-axis and magnetic field is along the positive x-axis. Then the direction of propagation of electromagnetic wave is:

The electric current in a circular coil of four turns produces a magnetic induction $32T$ at its centre. The coil is unwound and is rewound into a circular coil of single turn, the magnetic induction at the centre of the coil by the same current will be :

The equivalent resistance between $AandB$ of the network shown in figure: 

A capacitor of capacitance $900\mu F$ is charged by a $100V$ battery. The capacitor is disconnected from the battery and connected to another uncharged identical capacitor such that one plate of uncharged capacitor connected to positive plate and another plate of uncharged capacitor connected to negative plate of the charged capacitor. The loss of energy in this process is measured as $x\times {10}^{-2}J$. The value of $x$ is ______.

The charge flowing in a conductor changes with time as $Q(t)=\alpha t-\beta {t}^{2}+\gamma {t}^{3}$, where $\alpha ,\beta$ and $\gamma$ are constants. Minimum value of current is: