277 + Interview Questions in ELECTRO-MAGNETIC-INDUCTION IN GENERAL AWARENESS Page 5 InterviewSolution

201.	Why is soft iron preferred for making the core of a transformer?A. Hysteresis lossesB. Eddy current lossesC. Force opposing electric currentD. None of the above
Answer» Correct Answer - A

Discussion

202.	Assertion: Soft iron is used as transformer core. Reason: Soft iron has narrow hysteresis loop.A. If both assertion and reason are t rue and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is false.D. If the assertion and reason both are false
Answer» Correct Answer - A

Discussion

203.	A coil and a bulb are connected in series with a `dc` source, a soft iron core is then inserted in the coil. ThenA. Intensity of the bulb remains the sameB. Intensity of the bulb decreasesC. Intensity of the bulb increasesD. The bulb ceases to glow
Answer» Correct Answer - B

Discussion

204.	The self inductance of a coil is 5 henry , a current of 1 amp change to 2 amp within 5 second through the coil. The value of induced e.m.f. will beA. 10 voltB. 0.10 voltC. 1.0 voltD. 100 volt
Answer» Correct Answer - C

Discussion

205.	Two pure inductors each of self-inductance `L` are connected in parallel but are well separted from each other. The total inductance isA. `2L`B. LC. `(L)/(2)`D. `(L)/(4)`
Answer» Correct Answer - C

Discussion

206.	The number of turns of primary and secondary coils of a transformer are 5 and 10 respectively and the mutual inductance of the tranformar is 25 henry. Now the number of turns in the primary and secondary of the transformar are made 10 and 5 respectivaly. The mutual inductance of the transformar in henry will beA. 6.25B. 12.5C. 25D. 50
Answer» Correct Answer - C

Discussion

207.	Two circuits have coefficient of mutual induction of `0.09` henry. Average e.m.f. induced in the secondary by a change of current from `0` to `20` ampere in `0.006` second in the primary will beA. `120 V`B. `80V`C. `200 V`D. `300 V`
Answer» Correct Answer - D

Discussion

208.	In a transformer , the coefficient of mutual inductance between the primary and the secondary coil is `0.2` henry. When the current changes by `5` ampere//second in the primary, the induced e.m.f. in the secondary will beA. 5VB. 1VC. 25 VD. 10 V
Answer» Correct Answer - B

Discussion

209.	When the current in a coil changeg from `8` amperes to `2` amperes in `3xx10^(-2)` seconds, the e.m.f. induced in the coil is `2` volt. The self-inductance of the coil (in millihenry) isA. 1B. 5C. 20D. 10
Answer» Correct Answer - D

Discussion

210.	An e.m.f. of `12 "volts"` is induced in a given coil when the current in it changes at the rate of `48` amperes per minute. The self-inductance of the coil isA. 0.25 henryB. 15 henryC. 1.5 henryD. 9.6 henry
Answer» Correct Answer - B

Discussion

211.	A transformer has `100` turns in the primary coil and carries `8A` current. If input power is one kilowatt, the number of turns required in the secondary coil to have `500V` output will beA. 100B. 200C. 400D. 300
Answer» Correct Answer - C

Discussion

212.	A`50` volt potential difference is suddenly applied to a coil with `L=5xx10^(-3)` henry and `R=180 ohm`. The rate of increase of current after `0.001` second isA. `27.3 amp//sec`B. `27.8 amp//sec`C. `2.73 amp//sec`D. None of the above
Answer» Correct Answer - D

Discussion

213.	The ratio of secondary to the primary turns in a transformer is `3:2`. If the power output be `P`, then the input power neglecting all loses must be equal toA. `5P`B. `1.5 P`C. PD. `(2)/(5)P`
Answer» Correct Answer - C

Discussion

214.	A coil is wound as a transformer of rectangular cross section. If all the linear dimension of the transformer are increased by a factor `2` and the number of turns per unit length of the coil remain the same, the self-inductance increased by a factor ofA. 16B. 12C. 8D. 4
Answer» Correct Answer - C

Discussion

215.	Which of the following units denotes the dimension `(ML^(2))/(Q^(2))`, where Q denotes the electric charge?A. `Wb//m^(2)`B. henry `(H)`C. `H//m^(2)`D. weber `(Wb)`
Answer» Correct Answer - B

Discussion

216.	A `LC` circuit is in the state of resonace. If `C=0.1muF` and `L=0.25` henry. Neglecting ohmic resistance os circiut what is the frequency of oscillations?A. 1007 HzB. 100 HzC. 109 HzD. 500 Hz
Answer» Correct Answer - A

Discussion

217.	`5 cm` long solenoid having `10` ohm resistance and `5mH` induced is joined to a `10` volt battery. At steady state the current through the solenoid in apmpere will beA. 5B. 2C. 1D. Zero
Answer» Correct Answer - B

Discussion

218.	The square root of the product of inductance and capacitance has the dimension ofA. LengthB. MassC. TimeD. No dimension
Answer» Correct Answer - C

Discussion

219.	A coil having an inductance of 0.5 H 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 isA. 10B. 5C. 2.5D. 1.25
Answer» Correct Answer - C

Discussion

220.	A coil of inductance `300mh` and resistance `2Omega` is connected to a source of voltage `2V`. The current reaches half of its steady state value inA. 0.15 sB. 0.3 sC. 0.05 sD. 0.1 s
Answer» Correct Answer - D

Discussion

221.	A coil of inductance `300mh` and resistance `2Omega` is connected to a source of voltage `2V`. The current reaches half of its steady state value inA. `0.3 s`B. `0.15 s`C. `0.1 s`D. `0.05 s`
Answer» Correct Answer - C `L = 300 xx 10^(-3) H` `R = 10 Omega` `I = (I_(0))/(2)` Using `I = I_(0)(1-e^(-Rt//L))`, we get `(I_(0))/(2) = I_(0) (1-e^(-Rt//L))` `rArr (1)/(2) = 1 - e^(-Rt//L) rArr e^(-Rt//L) = (1)/(2)` `rArr e^(Rt//L) = 2 rArr (R )/(L)t = log_(e) 2 = 0.693` `rArr t = (0693 xx 300 xx 10^(-3))/(2)s = 0.1 s`

Discussion

222.	A coil having an area `2m^(2)` is placed in a magnetic field which changes from `1 Wb//m^(2)` to `4Wb//m^(2)` in an interval of `2` second. The average e.m.f. induced in the coil will beA. `4V`B. `3V`C. `1.5V`D. `2V`
Answer» Correct Answer - B `e = A(dB)/(dt)`

Discussion

223.	A transformer is used to step down a.c.voltage. What appliance do you use to step down d.c. voltage ?A. Change the alternating potentialB. Change the alternating currentC. To prevent the power loss in alternating current flowD. To increase the power of current source
Answer» Correct Answer - A

Discussion

224.	The alternating voltage induced in the secondary coil of a transformer is mainly due toA. A varying electric fieldB. A varying magnetic fieldC. The vibrations of the primary coilD. The iron core of the transformer
Answer» Correct Answer - B

Discussion

225.	A wire `KMN` moves along the bisector of the angle `theta` with a constant velocity `v` in a uniform magnetic field `B` perpendicular to the plane of the paper and directed inward. Which of the following is correct? A. Effective length of the wire is `2L "sin" theta/2`B. `E.m.f` induced between `K` and `N` is `2BLV "sin"(theta)/(2)`C. The shape of `KMN` is immaterial, only the end points `K N` are important.D. All the above
Answer» `e = B l_("eff")v , l_("eff") = 2(l sin^(theta)//_(2))`

Discussion

226.	A resistance with an inductor of `8 H` has the same time constant as it has with a condenser of capacitor `2 mu F`. The value of the resistance expressed in ohms isA. `500`B. `250`C. `4000`D. `2000`
Answer» Correct Answer - B `q = q_(0)(1-e^(-t//T)) , V = ((q)/(C ))`

Discussion

227.	A conducitng rod `AB` of length `l = 1 m` moving at a velcity `v = 4 m//s` making an angle `30^(@)` with its length. A uniform magnetic field `B = 2T` exists in a direction perpendicular to the plane of motion. Then : A. `V_(A) - V_(B) = 8V`B. `V_(A) - V_(B) = 4V`C. `V_(B) - V_(A) = 8V`D. `V_(B) - V_(A) = 4V`
Answer» Correct Answer - B `e = Blv sin theta`

Discussion

228.	In a primary coil `5A` current is flowing on `220` volts. In the secondary coil `2200V` voltage produces. Then ratio of number of turns in secondary coil and primary coil will beA. `1:10`B. `10:1`C. `1:1`D. `11:1`
Answer» Correct Answer - B

Discussion

229.	A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. The direction of induced current in wire `AB` and `CD` are A. B to A and D to CB. A to B and C to DC. A to B and D to CD. B to A and C to D
Answer» Correct Answer - A

Discussion

230.	A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. The direction of induced current in wire `AB` and `CD` are A. `B` to `A` and `D` to `C`B. `A` to `B` and `C` to `D`C. `A` to `B` and `D` to `C`D. `B` to `A` and `C` to `D`
Answer» Correct Answer - A

Discussion

231.	A magnetic flux through a stationary loop with a resistance `R` varies during the time interval `tau` as `phi=at(tau-t)`. Find the amount of the generated in the loop during that time
Answer» Given that `phi = at(T-t)`, induced emf, `E = (d phi)/(dt)` `= (d)/(dt)[at(T-t)], = at(0-1) + a(T-1), = a(T-2t)` So, induced emf is alos a function of time Heat generated `H = underset(0)overset(T)int(E^(2))/(R )dt` , `= (a^(2))/(R )underset(0)overset(T)int(T-2t)dt , = (a^(2)T^(3))/(3R)`

Discussion

232.	A magnetic flux through a stationary loop with a resistance `R` varies during the time interval `tau` as `phi=at(tau-t)`. Find the amount of the generated in the loop during that timeA. `(aT)/(3R)`B. `(a^(2)T^(2))/(3R)`C. `(a^(2)T^(2))/(R )`D. `(a^(2)T^(3))/(3R)`
Answer» Correct Answer - D Given that `phi = at (T-t)` induced emf, `E = (d phi)/(dt) = (d)/(dt)[at(T-t)]` `= at (0-1)+a(T-t) , = a(T-2t)` So, induced emf is alos a function of time. `:.` Heat generated in time `T` is `H = int_(0)^(T)(E^(2))/(R )dt = (a^(2))/(R ) int_(0)^(T)(T-2t)^(2)dt = (a^(2)T^(3))/(3R)`

Discussion

233.	The current in a coil of inductance `5H` decreases at the rate of `2A//s`. The induced e.m.f. isA. 2 VB. 5 VC. 10 VD. `-10 V`
Answer» Correct Answer - C

Discussion

234.	A coil of resistance `20Omega` and inductance `0.5H` is switched to `DC200V` supply. Calculate the rate of increase of current a. at the instant of closing the switch and b. after one time constant. c. Find the steady state current in the circuit.
Answer» `{:a)` This is the case of growth of current in an `L-R` circuit. Hence, current at time `t` is given by `i = i_(0)(1-e^((-t)/(tau_(L))))` Rate of increase of current, `(di)/(dt) = (i_(0))/(tau_(L))e^((-t)/(tau_(L)))`, At `t = 0(di)/(dt) = (i_(0))/(tau_(L)) = (E//R)/(L//R) = (E)/(L)` `(di)/(dt) = (200)/(0.5) = 400 A//s` `{:b)` At `t = tau_(L), (di)/(dt)(400)e^(-1) = (0.37)(400) = 148A//s` `{:c)` The steady state current in the circuit, is `i_(0) = (E)/(R ) = (200)/(20)10A`

Discussion

235.	Some magnetic flux is changed from a coil of resitance `10 Omega`. As a result, an induced current is developed it, which varies with time as shown in Fig. 3.213. Find the magnitude of the change in flux through ythe coil in weber. A. 2B. 4C. 6D. None of these
Answer» Correct Answer - A

Discussion

236.	If the current `30A` flowing in the primary coil is made zero in `0.1` sec. the emf induced in the secondary coil is `1.5` volt. The mutual inductance between the coil isA. `0.05 H`B. `1.05 H`C. `0.1 H`D. `0.2 H`
Answer» Correct Answer - A

Discussion

237.	An emf induced in a secondary coil is `10000 V` when the current breaks in the primary. The mutual inductance is `5 H` and the current reaches to zero in `10^(-4) s` in primary. The maximum current in the primary before the breaks isA. `0.2A`B. `0.3A`C. `0.4A`D. `0.5 A`
Answer» Correct Answer - A `e = L(di)/(dt) = 5((i_(1)-0)/(10^(-4)))`

Discussion

238.	The mutual inductance of an induction coil is 5H . In the primary coil, the current reduces from 5 A to zero in `10^(-3)s` . What is the induced emf in the secondary coilA. `2500 V`B. `25000 V`C. `2510 V`D. Zero
Answer» Correct Answer - B

Discussion

239.	Consider the situation shown in . if the switch is closed and after some time it is opened again, the closed loop will show A. an anticlockwise current-pulseB. a clockwise current-pulseC. an anticlockwise current-pulse and then a clockwise current-pulseD. a clockwise current-pulse and then an anticlockwise current-pulse
Answer» Correct Answer - D

Discussion

240.	Asseration: Acceleration of a magnet falling through a long soleneoid decreases. Reason: the induced current produced in a circuit always flow in such direction that it opposes the change or the cause the produced it.A. If both assertion and reason are t rue and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is false.D. If the assertion and reason both are false
Answer» Correct Answer - A

Discussion

241.	Assertion : The induced emf and current will be same in two identical loops of copper and aluminium, when rotated with same speed in the same magnetic field. Reason : Mutual induction does not depends on the orientation of the coilsA. Both `A` and `R` are true and `R` is the correct explanation of `A`B. Both `A` and `R` are true and `R` is not the correct explanation of `A`C. `A` is true but `R` is falseD. `A` is false but `R` is true.
Answer» Correct Answer - C

Discussion

242.	Asseration:Induced coil are made of copper. Reason:Induced current is more in wire having less resistance.A. If both assertion and reason are t rue and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is false.D. If the assertion and reason both are false
Answer» Correct Answer - A

Discussion

243.	Asseration:Magnetic flux can produce induce e.m.f. Reason:Faraday establishid induced e.m.f. experimentally.A. If both assertion and reason are t rue and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is false.D. If assertion is false but reason is true.
Answer» Correct Answer - D

Discussion

244.	Asseration:A spark occure between the poles of a switch when the switch is opened. Reason:current flowing in the conductor produces magnetic field.A. If both assertion and reason are t rue and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is false.D. If the assertion and reason both are false
Answer» Correct Answer - B

Discussion

245.	Statement-1 : The induced e.m.f. and current will be same in two identical loops of copper and aluminium, when rotated with same speed in the same magnetic field. Statement-2 : Induced e.m.f. is proportional to rate of change of magnetic field while induced current depends on resistance of wire.A. If both assertion and reason are t rue and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is false.D. If assertion is false but reason is true.
Answer» Correct Answer - D

Discussion

246.	Asseration:Self-inductance is called the inertia of electricity. Reason:self-inductance is the phenomenon, according to which an opposing induced e.m.f. is produced in a coil as a result of change in current or magnetic flux linked in the coil.A. If both assertion and reason are t rue and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is false.D. If the assertion and reason both are false
Answer» Correct Answer - B

Discussion

247.	A square loop of side `10 cm` and resistance `0.5 Omega` is placed vertically in the east-west plane. A uniform magnetic field of `0.10 T` is set up across the plane in the north-east direction. The magnetic field is decreased to zero in `0.70 s` at a steady rate. The magnetude of current in this time-interval is.
Answer» The initial magnetic field is given by `phi = BA cos theta` Given, `B = 0.10 T`, area of sqare loop `= 10 xx 10 = 100 cm^(2) = 10^(-2)m^(2)` `:. phi = (0.1 xx 10^(-2))/(sqrt(2))Wb` Final flux, `phi_("min") = 0` The change in flux is brought about in `0.70 s` The magnitude of the induced emf is `e = (Delta phi)/(Delta t) = (\|phi-0\|)/(Delta t) = (10^(-3))/(sqrt(2) xx 0.7) = 1mV` The magnitude of current is `I = (e )/(R ) = (10^(-3))/(0.5) = 2mA`

Discussion

248.	A coil of `N=100` turns and area `1cm^2` carries a current `I=5 A` and creates a magnetic flux `varphi=10^(-5)Tm^(-2)` .The value of its inductance `L` will beA. `0.05 mH`B. `0.10 mH`C. `0.15 mH`D. `0.20 mH`
Answer» Correct Answer - D

Discussion

249.	The current through choke coil increases form zero to 6 A in 0.3 seconds and an induced e.m.f. of 30 V is produced. The inductance of the coil of choke isA. 5 HB. 2.5 HC. 1.5 HD. 2H
Answer» Correct Answer - C

Discussion

250.	A square loop `ACDE` of area `20 cm^2 ` resistance `5Omega` is rotate in as magnetic field `B=2T` through `180^@` (a) in `0.01S` and (b) in `0.02 s` Find the magnitudes of averasge values of e i and `/_q` in both the cases.
Answer» Let the take the area vator `S` perpendicular to plane of loop inwards. So initially `dS` parallel to `B` and when it rorated by `180^(@)`, `S` is anti parallel to `B`. Hence, initial flux passing through the loop, `phi_(i) = BS cos 0^(@) = (2)(20 xx 10^(-4))(1)` `= 4 xx 10^(-3) Wb` Flux passing througn the loop when it rotated by `180^(@), phi_(f) = BS cos 180^(@)` `= (2) (20 xx 10^(-4))(-1) = -4.0 xx 10^(-3) Wb` Therefore, change in flux, `Delta phi_(B) = phi_(f)-phi_(i)`, `= -8 xx 10^(-3) Wb` (a) Given `Delta t = 0.01 s, R = 5 Omega` , `:. \|e\| = \|(Delta phi_(B))/(Delta t)\|` `= (8 xx 10^(-3))/(0.01) = 0.8V` , or `i = (\|e\|)/(R ) = (0.8)/(5) = 0.16 A` and `Delta q = i Delta t = 0.16 xx 0.01`, `= 1.6 xx 10^(-3) C` (b) `Delta t = 0.02 s`, `:. \|e\| = \|-(Delta phi_(B))/(Delta t)\|` `= (8 xx 10^(-3))/(0.02)`, `= 0.4V`, `i = = (\|e\|)/(R ) = (0.4)/(5) = 0.08A` and `Delta q = i Delta t = (0.08)(0.02)`, `= 16 xx 10^(-3)C`

Discussion

Explore topic-wise InterviewSolutions in .

Why is soft iron preferred for making the core of a transformer?A. Hysteresis lossesB. Eddy current lossesC. Force opposing electric currentD. None of the above

A coil and a bulb are connected in series with a `dc` source, a soft iron core is then inserted in the coil. ThenA. Intensity of the bulb remains the sameB. Intensity of the bulb decreasesC. Intensity of the bulb increasesD. The bulb ceases to glow

The self inductance of a coil is 5 henry , a current of 1 amp change to 2 amp within 5 second through the coil. The value of induced e.m.f. will beA. 10 voltB. 0.10 voltC. 1.0 voltD. 100 volt

Two pure inductors each of self-inductance `L` are connected in parallel but are well separted from each other. The total inductance isA. `2L`B. LC. `(L)/(2)`D. `(L)/(4)`

Two circuits have coefficient of mutual induction of `0.09` henry. Average e.m.f. induced in the secondary by a change of current from `0` to `20` ampere in `0.006` second in the primary will beA. `120 V`B. `80V`C. `200 V`D. `300 V`

In a transformer , the coefficient of mutual inductance between the primary and the secondary coil is `0.2` henry. When the current changes by `5` ampere//second in the primary, the induced e.m.f. in the secondary will beA. 5VB. 1VC. 25 VD. 10 V

When the current in a coil changeg from `8` amperes to `2` amperes in `3xx10^(-2)` seconds, the e.m.f. induced in the coil is `2` volt. The self-inductance of the coil (in millihenry) isA. 1B. 5C. 20D. 10

An e.m.f. of `12 "volts"` is induced in a given coil when the current in it changes at the rate of `48` amperes per minute. The self-inductance of the coil isA. 0.25 henryB. 15 henryC. 1.5 henryD. 9.6 henry

A transformer has `100` turns in the primary coil and carries `8A` current. If input power is one kilowatt, the number of turns required in the secondary coil to have `500V` output will beA. 100B. 200C. 400D. 300

A`50` volt potential difference is suddenly applied to a coil with `L=5xx10^(-3)` henry and `R=180 ohm`. The rate of increase of current after `0.001` second isA. `27.3 amp//sec`B. `27.8 amp//sec`C. `2.73 amp//sec`D. None of the above

The ratio of secondary to the primary turns in a transformer is `3:2`. If the power output be `P`, then the input power neglecting all loses must be equal toA. `5P`B. `1.5 P`C. PD. `(2)/(5)P`

A coil is wound as a transformer of rectangular cross section. If all the linear dimension of the transformer are increased by a factor `2` and the number of turns per unit length of the coil remain the same, the self-inductance increased by a factor ofA. 16B. 12C. 8D. 4

Which of the following units denotes the dimension `(ML^(2))/(Q^(2))`, where Q denotes the electric charge?A. `Wb//m^(2)`B. henry `(H)`C. `H//m^(2)`D. weber `(Wb)`

A `LC` circuit is in the state of resonace. If `C=0.1muF` and `L=0.25` henry. Neglecting ohmic resistance os circiut what is the frequency of oscillations?A. 1007 HzB. 100 HzC. 109 HzD. 500 Hz

`5 cm` long solenoid having `10` ohm resistance and `5mH` induced is joined to a `10` volt battery. At steady state the current through the solenoid in apmpere will beA. 5B. 2C. 1D. Zero

The square root of the product of inductance and capacitance has the dimension ofA. LengthB. MassC. TimeD. No dimension

A coil having an inductance of 0.5 H 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 isA. 10B. 5C. 2.5D. 1.25

A coil of inductance `300mh` and resistance `2Omega` is connected to a source of voltage `2V`. The current reaches half of its steady state value inA. 0.15 sB. 0.3 sC. 0.05 sD. 0.1 s

A coil of inductance `300mh` and resistance `2Omega` is connected to a source of voltage `2V`. The current reaches half of its steady state value inA. `0.3 s`B. `0.15 s`C. `0.1 s`D. `0.05 s`

A coil having an area `2m^(2)` is placed in a magnetic field which changes from `1 Wb//m^(2)` to `4Wb//m^(2)` in an interval of `2` second. The average e.m.f. induced in the coil will beA. `4V`B. `3V`C. `1.5V`D. `2V`

A transformer is used to step down a.c.voltage. What appliance do you use to step down d.c. voltage ?A. Change the alternating potentialB. Change the alternating currentC. To prevent the power loss in alternating current flowD. To increase the power of current source

The alternating voltage induced in the secondary coil of a transformer is mainly due toA. A varying electric fieldB. A varying magnetic fieldC. The vibrations of the primary coilD. The iron core of the transformer

A resistance with an inductor of `8 H` has the same time constant as it has with a condenser of capacitor `2 mu F`. The value of the resistance expressed in ohms isA. `500`B. `250`C. `4000`D. `2000`

In a primary coil `5A` current is flowing on `220` volts. In the secondary coil `2200V` voltage produces. Then ratio of number of turns in secondary coil and primary coil will beA. `1:10`B. `10:1`C. `1:1`D. `11:1`

A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. The direction of induced current in wire `AB` and `CD` are A. B to A and D to CB. A to B and C to DC. A to B and D to CD. B to A and C to D

A magnetic flux through a stationary loop with a resistance `R` varies during the time interval `tau` as `phi=at(tau-t)`. Find the amount of the generated in the loop during that time

A magnetic flux through a stationary loop with a resistance `R` varies during the time interval `tau` as `phi=at(tau-t)`. Find the amount of the generated in the loop during that timeA. `(aT)/(3R)`B. `(a^(2)T^(2))/(3R)`C. `(a^(2)T^(2))/(R )`D. `(a^(2)T^(3))/(3R)`

The current in a coil of inductance `5H` decreases at the rate of `2A//s`. The induced e.m.f. isA. 2 VB. 5 VC. 10 VD. `-10 V`

A coil of resistance `20Omega` and inductance `0.5H` is switched to `DC200V` supply. Calculate the rate of increase of current a. at the instant of closing the switch and b. after one time constant. c. Find the steady state current in the circuit.

Some magnetic flux is changed from a coil of resitance `10 Omega`. As a result, an induced current is developed it, which varies with time as shown in Fig. 3.213. Find the magnitude of the change in flux through ythe coil in weber. A. 2B. 4C. 6D. None of these

If the current `30A` flowing in the primary coil is made zero in `0.1` sec. the emf induced in the secondary coil is `1.5` volt. The mutual inductance between the coil isA. `0.05 H`B. `1.05 H`C. `0.1 H`D. `0.2 H`

An emf induced in a secondary coil is `10000 V` when the current breaks in the primary. The mutual inductance is `5 H` and the current reaches to zero in `10^(-4) s` in primary. The maximum current in the primary before the breaks isA. `0.2A`B. `0.3A`C. `0.4A`D. `0.5 A`

The mutual inductance of an induction coil is 5H . In the primary coil, the current reduces from 5 A to zero in `10^(-3)s` . What is the induced emf in the secondary coilA. `2500 V`B. `25000 V`C. `2510 V`D. Zero

A coil of `N=100` turns and area `1cm^2` carries a current `I=5 A` and creates a magnetic flux `varphi=10^(-5)Tm^(-2)` .The value of its inductance `L` will beA. `0.05 mH`B. `0.10 mH`C. `0.15 mH`D. `0.20 mH`

The current through choke coil increases form zero to 6 A in 0.3 seconds and an induced e.m.f. of 30 V is produced. The inductance of the coil of choke isA. 5 HB. 2.5 HC. 1.5 HD. 2H

A square loop `ACDE` of area `20 cm^2 ` resistance `5Omega` is rotate in as magnetic field `B=2T` through `180^@` (a) in `0.01S` and (b) in `0.02 s` Find the magnitudes of averasge values of e i and `/_q` in both the cases.