Electromagnetism PYQ — Page 23

A metallic rod of length $L$ is rotated with an angular speed of $\omega$ normal to a uniform magnetic field $B$ about an axis passing through one end of rod as shown in figure. The induced emf will be : .

In the given circuit.${C}_{1}=2\mu F,{C}_{2}=0.2\mu F,{C}_{3}=2\mu F,{C}_{4}=4\mu F,{C}_{5}=$ $2\mu F,{C}_{6}=2\mu F$. The charge stored on capacitor ${C}_{4}$ is ______ $\mu C$. 

The magnetic field B crossing normally a square metallic plate of area $4{m}^{2}$ is changing with time as shown in figure. The magnitude of induced emf in the plate during $t=2s$ to $t=4s$, is _____ $mV$. 

 The current flowing through ${R}_{2}$ is :

Two concentric circular coils with radii $1\mathrm{cm}$ and $1000\mathrm{cm}$ and number of turns $10$ and $200$ respectively are placed coaxially with centers coinciding. The mutual inductance of this arrangement will be _____ $\times {10}^{–8}H$. (Take, ${\pi }^{2}=10$)

Certain galvanometers have a fixed core made of non magnetic metallic material. The function of this metallic material is

A solenoid of $1200$ turns is wound uniformly in a single layer on a glass tube $2m$ long and $0.2m$ in diameter. The magnetic intensity at the center of the solenoid when a current of $2A$ flows through it is:

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$. Assertion A : Electromagnets are made of soft iron. Reason R : Soft iron has high permeability and low retentivity. In the light of above statements, choose the most appropriate answer from the options given below.

Graphical variation of electric field due to a uniformly charged insulating solid sphere of radius $R,$with distance $r$ from the centre $O$ is represented by: 

If two charges ${q}_{1}$and ${q}_{2}$ are separated with distance $d$ and placed in a medium of dielectric constant $k$. What will be the equivalent distance between charges in air for the same electrostatic force?

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R Assertion A : EM waves used for optical communication have longer wavelengths than that of microwave, employed in Radar technology. Reason R : Infrared EM waves are more energetic than microwaves, (used in Radar) In the light of given statements, choose the correct answer from the options given below.

A massless square loop, of wire of resistance $10\Omega$, supporting a mass of $1g$, hangs vertically with one of its sides in a uniform magnetic field of ${10}^{3}G$, directed outwards in the shaded region. A dc voltage $V$ is applied to the loop. For what value of $V$, the magnetic force will exactly balance the weight of the supporting mass of $1g$? (If sides of the loop $=10\mathrm{cm},g=10m{s}^{-2}$) .

A network of four resistances is connected to $9V$ battery, as shown in figure. The magnitude of voltage difference between the points $A$ and $B$ is __________ $V$. 

In the circuit shown, the energy stored in the capacitor is $n\mu J$. The value of $n$ is _____. 

A long straight wire of circular cross-section (radius $a$) is carrying steady current $I.$ The current $I$ is uniformly distributed across this cross-section. The magnetic field is

A uniform electric field of $10N{C}^{-1}$ is created between two parallel charged plates (as shown in figure). An electron enters the field symmetrically between the plates with a kinetic energy $0.5\mathrm{eV}.$ The length of each plate is $10\mathrm{cm}$. The angle $(\theta )$ of deviation of the path of electron as it comes out of the field is ______(in degree). 

Electric potential at a point $P$ due to a point charge of $5\times {10}^{-9}C$ is $50V$. The distance of $P$ from the point charge is: (Assume, $\frac{1}{4\pi {\epsilon }_{0}}=9\times {10}^{9}N{m}^{2}{C}^{-2}$)

The energy of an electromagnetic wave contained in a small volume oscillates with

Which of the following correctly represents the variation of electric potential $(V)$ of a charged spherical conductor of radius $(R)$ with radial distance $(r)$ from the centre?

Match List I with List II <table class="pyq-table"><tbody><tr><td colspan="2" rowspan="1">List – I (Current configuration)</td><td colspan="2" rowspan="1">List – II (Magnetic field at point $O$)</td></tr><tr><td>A</td><td><img src="https://prepforbharat.s3.ap-south-1.amazonaws.com/exam/615f0e999476412f48314daf/Physics/images/Magnetic_Effects_of_Current/648b5a6f417cc3fb48d68059/question_1__q_648b5a6f417cc3fb48d68059__cdn-question-pool.getmarks.app__6d4d8a8b-2cf2-4134-983a-f4d799603481-30c03559-a817-48e9-903a__ea5c80dc0b_final_ppt_sync.png" alt="JEE Main 2023 Physics, Magnetic Effects of Current — question figure 1"></td><td>I.</td><td>${B}_{0}=\frac{{\mu }_{0}I}{4\pi r}[\pi +2]$</td></tr><tr><td>B</td><td><img src="https://prepforbharat.s3.ap-south-1.amazonaws.com/exam/615f0e999476412f48314daf/Physics/images/Magnetic_Effects_of_Current/648b5a6f417cc3fb48d68059/question_2__q_648b5a6f417cc3fb48d68059__cdn-question-pool.getmarks.app__fa41edbe-9bec-4bce-b977-38641dda9526-9894246_B__1d8500f970_final_ppt_sync.png" alt="JEE Main 2023 Physics, Magnetic Effects of Current — question figure 2"></td><td>II.</td><td>${B}_{0}=\frac{{\mu }_{0}}{4}\frac{I}{r}$</td></tr><tr><td>C</td><td><img src="https://prepforbharat.s3.ap-south-1.amazonaws.com/exam/615f0e999476412f48314daf/Physics/images/Magnetic_Effects_of_Current/648b5a6f417cc3fb48d68059/question_3__q_648b5a6f417cc3fb48d68059__cdn-question-pool.getmarks.app__0455c956-7478-44d1-aafb-f6da4de894cc-9894246_C__68b5fd56ef_final_ppt_sync.png" alt="JEE Main 2023 Physics, Magnetic Effects of Current — question figure 3"></td><td>III.</td><td>${B}_{0}=\frac{{\mu }_{0}I}{2\pi r}[\pi -1]$</td></tr><tr><td>D</td><td><img src="https://prepforbharat.s3.ap-south-1.amazonaws.com/exam/615f0e999476412f48314daf/Physics/images/Magnetic_Effects_of_Current/648b5a6f417cc3fb48d68059/question_4__q_648b5a6f417cc3fb48d68059__cdn-question-pool.getmarks.app__514b245c-d49c-45f0-bee9-5eeea479953f-9894246_D__0d22150df7_final_ppt_sync.png" alt="JEE Main 2023 Physics, Magnetic Effects of Current — question figure 4"></td><td>IV.</td><td>${B}_{0}=\frac{{\mu }_{0}I}{4\pi r}[\pi +1]$</td></tr></tbody></table>Choose the correct answer from the option given below:

The energy density associated with electric field $\vec{E}$ and magnetic field $\vec{B}$ of an electromagnetic wave in free space is given by (${\epsilon }_{0}-$ permittivity of free space, ${\mu }_{0}-$ permeability of free space)

In the given circuit, the equivalent resistance between the terminal A and B is ____ $\Omega$ 

A straight wire AB of mass $40g$ and length $50\mathrm{cm}$ is suspended by a pair of flexible leads in uniform magnetic field of magnitude $0.40T$ as shown in the figure. The magnitude of the current required in the wire to remove the tension in the supporting leads is _____ $A$. (Take $g=10m{s}^{-2})$. 

A current carrying circular loop of radius R produces a magnetic field B at its center. At what distance from center on its axis, the magnetic field becomes B/8?