Question 1 :
A low-loss transformer has 230 V applied to the primary and gives 4.6 V in the secondary. Secondary is connected to a load, which draws 5 A of current. The current (in ampere) in the primary is
Question 2 :
For a series <i>L-C-R</i> circuit at resonance, the statement which is not true is
Question 3 :
When the current changes from +2 A to -2 A in 0.05 s, an emf of 8 V is induced in a coil. The coefficient of self-induction of the coil is
Question 5 : Two inductors of inductance <img style='object-fit:contain' width=8 height=20 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea2a1198ab67a08eba56172"> each are connected in series with opposite magnetic fluxes. What is the resultant inductance? (Ignore mutual inductance)
Question 6 : If a charge in current of <img style='object-fit:contain' width='40' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea289498ab67a08eba54cbd"> in one coil produces a change in magnetic flux of <img style='object-fit:contain' width='89' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea289498ab67a08eba54cbe"> in the other coil, then the mutual inductance of the two coils in henry is
Question 7 : Three identical ring move with the same speed on a horizontal surface in a uniform horizontal magnetic field normal to the planes of the rings. The first <img style='object-fit:contain' width=22 height=20 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea2a1b301a30b595549731a"> slips without rolling, the second (B) rolls without slipping, and the third rolls with slipping
Question 8 : In a primary coil <img style='object-fit:contain' width='18' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea2891a3c680714de9a83b0"> current is flowing on 220 volts. In the secondary coil <img style='object-fit:contain' width='42' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea289f08ab67a08eba54e52"> voltage produces. Then ratio of number of turns in secondary coil and primary coil will be
Question 9 : An electron moves along the line <i>PQ</i> which lies in the same plane as a circular loop of conducting wire as shown in figure. What will be the direction of the induced current in the loop?<br> <img style='object-fit:contain' width='131' height='86' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28a533c680714de9a8735">
Question 10 :
The number of turns of primary and secondary coils of a transformer is 5 and 10 respectively and mutual inductance of the transformer is 25 H. Now, number of turns in primary and secondary are made 10 and 5 respectively. Mutual inductance of transformer will be
Question 11 :
The ratio of turns in primary and secondary coils of a transformer is 1 : 20. The ratio of currents in primary and secondary coils will be
Question 12 :
If coefficient of self induction of a coil is 1 H, an emf of 1 V is induced, if
Question 13 :
An irregular closed loop carrying a current has a shape such that the entire loop cannot lie in a single plane. If this is placed in a uniform magnetic field, the force acting on the loop
Question 14 :
The primary winding of a transformer has 200 turns and its secondary winding has 50 turns. If the current in the secondary winding is 40 A, the current in the primary is
Question 16 :
The number of turns in the primary coil of a transformer is 200 and the number of turns in secondary coil is 10. If 240 V AC is applied to the primary, the output from secondary will be
Question 17 :
When the rate of change of current is unity, induced emf is equal to
Question 21 : A coil having an inductance of <img style='object-fit:contain' width='34' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea289e48ab67a08eba54e13"> carries a current which is uniformly varying from zero to 10 ampere in 2 second. The e.m.f. (in volts) generated in the coil is
Question 22 :
If the current is halved in a coil, then the energy stored is how much times the previous value
Question 24 :
A bulb and a capacitor are in series with an ac source. On increasing frequency how will glow of the bulb change
Question 25 :
A long horizontal metallic rod with length along the east-west direction is falling under gravity. The potential difference between its two ends will
Question 26 :
Two circuits have mutual inductance of 0.09 H. Average emf induced in the secondary by a change of current from 0 to 20 A in 0.006 s in primary will be
Question 29 :
A step-up transformer is used on a 120 V line to provide a potential difference of 2400 V. If the primary coil has 75 turns, the number of turns in the secondary coil is
Question 30 :
An electric heater rated 220 V and 550 W is connected to A.C. mains. The current drawn by it is
Question 32 :
For a large industrial city with much load variations the DC generator should be
Question 33 :
Using an A.C. voltmeter the potential difference in the electrical line in a house is read to be 234 volt. If the line frequency is known to be 50 cycles/second, the equation for the line voltage is
Question 34 : A conducting ring is placed around the core of an electromagnet as shown in fig. when key <img style='object-fit:contain' width='11' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea289773c680714de9a84f8"> is pressed, the ring<br>
Question 35 : In an <i>R-C</i> circuit while charging, the graph of ln<i>I versus</i> time is as shown by the dotted line in the adjoining diagram where <i>I</i> is the current. When the value of the resistance is doubled, which of the solid curves best represents the variation of ln <i>I</i> <i>versus</i> time?<br> <img style='object-fit:contain' width=182 height=140 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea2a1288ab67a08eba561cf">
Question 36 :
A thin circular ring of area {tex} A {/tex} is held perpendicular to a uniform magnetic field of induction B. A small cut is made in the ring and a galvanometer is connected across the ends such that the total resistance of the circuit is {tex} R {/tex} . When the ring is suddenly squeezed to zero area, the charge flowing through the galvanometer is
Question 38 :
An ideal coil of 10{tex} \mathrm { H } {/tex} is connected in series with a resistance of 5{tex} \Omega {/tex} and a battery of 5{tex} \mathrm { V } {/tex} . 2 second after the connection is made, the current flowing in ampere in the circuit is
Question 39 :
A metallic ring connected to a rod oscillates freely like a pendulum. If now a magnetic field is applied in horizontal direction so that the pendulum now swings through the field, the pendulum will<br>
Question 40 :
Which of the following components of a <i>L C R </i>circuit, with AC supply, dissipates energy?
Question 41 : Current from <img style='object-fit:contain' width='53' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28a1a8ab67a08eba54ede"> in the straight wire is decreasing. The direction of induced current in the loop, is<br> <img style='object-fit:contain' width='126' height='66' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea289143c680714de9a838d">
Question 42 :
Turn ratio is 1.25. The step up transformer operates at 230 V and current through secondary is 2 A. Then current in primary is
Question 43 :
A coil of inductance 300{tex} \mathrm { mH } {/tex} and resistance 2{tex} \Omega {/tex} is connected to a source of voltage 2{tex} \mathrm { V } {/tex} . The current reaches half of its steady state value in
Question 44 :
A cylindrical bar magnet is kept along the axis of a circular coil. If the magnet is rotated about its axis, then
Question 45 :
A magnet is dropped down an infinitely long vertical copper tube
Question 46 : A loop of area 0.1 <img style='object-fit:contain' width='19' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea28ae23c680714de9a88a8"> rotates with a speed of 60 rps perpendicular to a magnetic field of 0.4 T. If there are 100 turns in the loop, maximum voltage induced in the loop is
Question 47 : The phase difference between the alternating current and emf is <img style='object-fit:contain' width=24 height=20 src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea2a19d4304d056cccda1da"> . Which of the following cannot be the constituent of the circuit?
Question 48 :
There is a uniform magnetic field directed perpendicular and into the plane of the paper. An irregular shaped conducting loop is slowly changing into a circular loop in the plane of the paper. Then
Question 49 :
In a series resonant LCR circuit, the voltage across {tex} R {/tex} is 100 volts and {tex} R = 1 \mathrm { k } \Omega {/tex} with {tex} \mathrm { C } = 2 \mu \mathrm { F } {/tex} . The resonant frequency {tex} \omega {/tex} is {tex} \mathrm {200 rad } / \mathrm { s } {/tex} . At resonance, the voltage across {tex} L {/tex} is
Question 50 : In the circuit shown, when the switch is closed, the capacitor charges with a time constant<br><img style='object-fit:contain' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5d60f09ad3eb695bc07eb5a7"><br>
Question 51 :
The Self-induced emf of a coil is 25 volts, When the current in it is changed at uniform rate from 10 A to 25 A in 1s, the change in the energy of the inductance is :
Question 53 : An inductor of inductance {tex} L = 400 \mathrm { mH } {/tex} and resistors of resistance {tex} R _ { 1 } = 2 \Omega {/tex} and {tex} \mathrm { R } _ { 2 } = 2 \Omega {/tex} are connected to a battery of emf 12{tex} \mathrm { V } {/tex} as shown in the figure. The internal resistance of the battery is negligible. The switch {tex} S {/tex} is closed at {tex} t = 0 . {/tex} The potential drop across {tex} L {/tex} as a function of time is<br><img style='object-fit:contain' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5d60eff0e5db655bbf10a57b"><br>
Question 54 :
A metal conductor of length 1 m rotates vertically about one of its ends at angular velocity 5 radians per second. If the horizontal component of earth's magnetic field is {tex} 0.2 \times 10 ^ { - 4 } \mathrm { T } {/tex} , then the e.m.f. developed between the two ends of the conductor is
Question 55 : Two identical coaxial circular loops carry current <img style='object-fit:contain' width='5' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea289153c680714de9a8390"> each circulating in the clockwise direction. If the loops are approaching each other, then
Question 56 :
A transformer rated at 10k W is used to connect a 5 kV transmission line to a 240 V circuit. The ratio of turns in the windings of the transformer is
Question 57 :
Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon
Question 58 :
A magnet is brought towards a coil (i) speedly (ii) slowly, then the induced e.m.f /induced charge will be respectively
Question 59 :
What is self inductance of a coil which produces 5V, when current in it changes from 3 A to 2 A in one millisecond?
Question 60 :
A 50 V AC is applied across an R-C (series) network. The rms voltage across the resistance is 40 V, then the potential across the capacitance would be
Question 62 :
The magnetic flux (in weber) linked with a coil of resistance 10{tex} \Omega {/tex} is varying with respect to time {tex} t {/tex} as {tex} \phi = 4 t ^ { 2 } + 2 t + 1 . {/tex} Then the current in the coil at time {tex} t = 1 {/tex} second is
Question 63 :
A metal disc of radius {tex} \mathrm {100 cm } {/tex} is rotated at a constant angular speed of {tex} \mathrm {60rad } / \mathrm { s } {/tex} in a plane at right angles to an external field of magnetic induction {tex}0.05 \ \mathrm { Wb } / \mathrm { m } ^ { 2 } {/tex} . The emf induced between the centre and a point on the rim will be
Question 64 : In a transformer 220 ac voltage is increased to <img style='object-fit:contain' width='69' height='20' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5ea2892d8ab67a08eba54c15"> . If the number of turns in the secondary are 2000, then the number of turns in the primary will be
Question 65 :
The tuning circuit of a radio receiver has a resistance of {tex} 50 \Omega , {/tex} an inductor of 10{tex} \mathrm { mH } {/tex} and a variable capacitor. A 1 MHz radio wave produces a potential difference of 0.1{tex} \mathrm { mV } {/tex} . The values of the capacitor to produce resonance is {tex} \left. \text { (Take } \pi ^ { 2 } = 10 \right) {/tex}
Question 66 :
Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-sectional area A = 10 {tex}cm^{2}{/tex} and length = 20 cm. If one of the solenoid has 300 turns and the other 400 turns, their mutual inductance is {tex}(\mu_{0} = 4\pi \times 10^{-7} Tm A^{-1}{/tex})
Question 67 :
Two solenoids of equal number of turns have their lengths and the radii in the same ratio {tex} 1 : 2 . {/tex} The ratio of their self inductances will be
Question 68 :
A metal rod of length 1 cuts across a uniform magnetic field B with a velocity <b>v</b>. If the resistance of the circuit of which the rod forms a part is <b>r</b>, then the force required to move the rod is
Question 69 :
In an alternating current circuit in which an inductance and capacitance are joined in series, current is found to be maximum when the value of inductance is 0.5 henry and the value of capacitance is 8{tex} \mu \mathrm { F } {/tex} . The angular frequency of applied alternating voltage will be
Question 70 : The resistance in the following circuit is increased at a particular instant. At this instant the value of resistance is 10{tex} \Omega {/tex} . The current in the circuit will be now<br> <img style='object-fit:contain' src='https://storage.googleapis.com/teachmint/question_assets/NEET/5ef1f6ea5db1ae4bc20c15d6' class="uploaded-image" />
Question 71 :
For an LCR series circuit with an A.C. source of angular frequency ω
Question 72 :
If rotational velocity of a dynamo armature is doubled, then induced e.m.f. will become
Question 73 :
A cylindrical bar magnet is kept along the axis of a circular coil. The magnet is rotated about its axis such that north pole faces the coil. The induced current in the coil
Question 74 :
The coil of dynamo is rotating in a magnetic field. The developed induced e.m.f. changes and the number of magnetic lines of force also changes. Which of the following conditions is correct
Question 75 :
In an AC generator, a coil with N turns, all of the same area A and total resistance R, rotates with frequency in a magnetic field B. The maximum value of emf generated in the coil is
Question 76 :
A circular wire of radius r rotates about its own axis with angular speed {tex} \omega {/tex} in a magnetic field B perpendicular to its plane, then the induced e.m.f. is
Question 77 : For the circuit shown in the fig., the current through the inductor is 0.9 A while the current through the condenser is 0.4 A. Then<br><img style='object-fit:contain' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5d60efc8e5db655bbf10a52b"><br>
Question 78 :
In an ideal transformer, the voltage is stepped down from 11 kV to 220 V. If the primary current be 100 A, the current in the secondary should be
Question 79 :
The primary and secondary coil of a transformer have <b>50</b> and <b>1500</b> turns respectively. If the magnetic flux Φ linked with the primary coil is given by Φ = Φ<sub>0</sub> + 4 t ,where Φ is in webers, <i><b>t</i></b> is time in seconds and Φ<sub>0</sub> is a constant, the output voltage across the secondary coil is
Question 80 :
A conducting ring of radius 1{tex} \mathrm { m } {/tex} kept in a uniform magnetic field {tex} B {/tex} of {tex} 0.01 T , {/tex} rotates uniformly with an angular velocity 100{tex} \mathrm { rad } \mathrm { s } ^ { - 1 } {/tex} with its axis of rotation perpendicular to {tex} B {/tex} . The maximum induced emf in it is
Question 81 : The figure shows certain wire segments joined together to form a coplanar loop. The loop is placed in a perpendicular magnetic field in the direction going into the plane of the figure. The magnitude of the field increases with time. {tex}I_{1}{/tex} and {tex}I_{2}{/tex} are the currents in the segments ab and cd. Then, <br>
<img style='object-fit:contain' src='https://storage.googleapis.com/teachmint/question_assets/NEET/5eb2813ccd357a12648729b9' class="uploaded-image" /> <br>
Question 82 :
Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon
Question 83 :
In an A.C. generator, when the plane of the armature is perpendicular to the magnetic field
Question 84 :
An AC generator of 220 V having internal resistance {tex} r = 10 \Omega {/tex} and external resistance {tex} R = 100 \Omega {/tex} . What is the power developed in the external circuit?
Question 85 : A conducting square frame of side <i><b>'a'</b></i> and a long staight wire carrying current <b> I </b>are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity <b> V </b>. The emf induced in the frame will be proportional to<br><img style='object-fit:contain' src="https://storage.googleapis.com/teachmint/question_assets/NEET/5d60f188d3eb695bc07eb618"><br>
Question 87 :
The self inductance of a long solenoid cannot be increased by
Question 88 :
The current in a {tex} L R {/tex} circuit builds up to {tex} \frac { 3 } { 4 } \mathrm { th } {/tex} of its steady state value in 4{tex} \mathrm { s } {/tex} . The time constant of this circuit is
Question 89 :
When the current changes from {tex} + 2 \mathrm { A } {/tex} to {tex} - 2 \mathrm { A } {/tex} in 0.05 second, an e.m.f. of 8{tex} \mathrm { V } {/tex} is induced in a coil. The coefficient of self- induction of the coil is
Question 90 : In a coil of resistance 100Ω a current is induced by changing the magnetic flux through it as shown in the figure The magnitude of change in flux through the coil is<br><center> <img style='object-fit:contain' src='https://storage.googleapis.com/teachmint/question_assets/NEET/5ece4d87eab619455fcb78b4' class="uploaded-image" height="120" /></center>
Question 91 :
A horizontal straight wire 20{tex} \mathrm { m } {/tex} long extending from east to west falling with a speed of 5.0{tex} \mathrm { m } / \mathrm { s } {/tex} , at right angles to the horizontal component of the earth's magnetic field {tex} 0.30 \times 10 ^ { - 4 } \mathrm { Wb } / \mathrm { m } ^ { 2 } {/tex} . The instantaneous value of the e.m.f. induced in the wire will be
Question 92 :
In an A.C. circuit, the current flowing in inductance is {tex} \mathrm { I } = 5 \sin ( 100 \mathrm { t } - \pi / 2 ) {/tex} amperes and the potential difference is {tex} \mathrm { V } = 200 \sin ( 100 \mathrm { t } ) {/tex} volts. The power consumption is equal to
Question 93 :
A step down transformer reduces <b>220 V</b> to <b>110 V</b> . The primary draws <b>5 A</b> of current and secondary supplies <b>9 A</b>. The efficiency of transformer is
Question 94 :
The mutual inductance of a pair of coils, each of N turns, is M henry. If a current of I ampere in one of the coils is brought to zero in t second, the emf induced per turn in the other coil, in volt, will be
Question 95 :
A magnetic field of {tex}2\times 10^{-2}{/tex} T acts at right angles to a coil of area {tex}100 cm^{2}{/tex}, with 50 turns. The average e.m.f induced in the coil is 0.1 V when it is removed from the field in t sec. The value of t is
Question 96 :
A copper disc of radius 0.1{tex} \mathrm { m } {/tex} rotated about its centre with 10 revolutions per second in a uniform magnetic field of 0.1 tesla with its plane perpendicular to the field. The e.m.f. induced across the radius of disc is
Question 97 :
Two conducting circular loops of radii {tex} \mathrm { R } _ { 1 } {/tex} and {tex} \mathrm { R } _ { 2 } {/tex} are placed in the same plane with their centres coinciding. If {tex} \mathrm { R } _ { 1 } > > \mathrm { R } _ { 2 } , {/tex} the mutual inductance {tex} \mathrm { M } {/tex} between them will be directly proportional to
Question 98 :
A bulb is rated at {tex} 100 \mathrm { V } , 100 \mathrm { W } {/tex}, it can be treated as a resistor. Find out the inductance of an inductor (called choke coil) that should be connected in series with the bulb to operate the bulb at its rated power with the help of an ac source of {tex} \mathrm {200 V } {/tex} and {tex} \mathrm { 50Hz } {/tex} .
Question 99 :
An ac source of angular frequency {tex} \omega {/tex} is fed across a resistor r and a capacitor {tex} C {/tex} in series. The current registered is I. If now the frequency of source is changed to {tex}\large \frac {\omega}{3} {/tex} (but maintaining the same voltage), the current in the circuit is found to be halved. The ratio of reactance to resistance at the original frequency {tex} \omega {/tex} is
Question 100 : As a result of change in the magnetic flux linked to the closed loop shown in the fig, an
e.m.f. V volt is induced in the loop. The work done (joule) in taking a charge Q coulomb
once along the loop is <br> <img style='object-fit:contain' src="https://data-screenshots.sgp1.digitaloceanspaces.com/5d6105709c699b6d4e70033b.jpg" />
Question 101 :
The pointer of a dead-beat galvanometer gives a steady deflection because
Question 102 : A metallic square loop ABCD is moving in its own plane with velocity v in a uniform magnetic field perpendicular to its plane as shown in figure. An electric field is induced <br> <img style='object-fit:contain' src="https://data-screenshots.sgp1.digitaloceanspaces.com/5d61014570b43a6d486d17c8.jpg" />
Question 103 :
Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon
Question 104 : Two different wire loops are concentric and lie in the same plane. The current in
the outer loop (I) is clockwise and increases with time. The induced current in the inner loop <br><img style='object-fit:contain' src="https://data-screenshots.sgp1.digitaloceanspaces.com/5d6105b49c699b6d4e70033f.jpg" />
Question 105 :
A metal ring is held horizontally and bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet
