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This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 201. |
Write the formula for magnetic flux passing through an Area A with an angle θ. |
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Answer» Flux ΦV= BA cos θ |
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| 202. |
The magnetic flux passing through unit area taken perpendicular to the field is called ………………… A) magnetic flux B) magnetic flux density C) magnetic field induction D) both B and C |
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Answer» D) both B and C |
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| 203. |
A metal ring is inserted through the soft iron cylinder which is wounded with copper wire. When DC is supplied between the ends of the coil, then ……………………. A) the metal ring is levitated on the coil and stays there. B) the metal ring is levitated and falls down immediately. C) the metal ring rotate round the cylinder at the same position.D) none |
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Answer» B) the metal ring is levitated and falls down immediately. |
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| 204. |
In above problem if foil is connected to any one plate of capacitor by means of conducting wire then capacitance of capacitor becomes -A. `2C`B. `C`C. `C//2`D. zero |
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Answer» Correct Answer - A |
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| 205. |
An inductor (L) and resistance (R) are connected in series with an AC source. The phase difference between voltage (V) and current (i) is `45^(@)`. Now a capacitor (C) is connected in series with L-R, If the phase difference between V and i remain same, then capacitive reactance and impedance of L-C-R circuit will be-A. `R//Rsqrt(2)`B. `2R,Rsqrt(2)`C. `R,R`D. `2R,Rsqrt(3)` |
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Answer» Correct Answer - B |
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| 206. |
In an `LR`-circuit, the inductive reactance is equal to the resistance `R` of the circuit. An e.m.f `E=E_(0)cos (omegat)` applied to the circuit. The power consumed in the circuit isA. `E_(0)^(2)//R`B. `E_(0)^(2)//2R`C. `E_(0)^(2)//4R`D. `E_(0)^(2)//8R` |
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Answer» Correct Answer - C |
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| 207. |
A generator of 100 V (rms) is connected in an ac circuit and 1 A (rms) current is flowing in the circuit. If the phase difference between the voltage and the current is `pi//3`. then the average power consumption and the power factor of the circuit will be –A. `50 W, 0.86`B. `100 W, 0.86`C. `100 W, 0.5`D. `50 W, 0.5` |
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Answer» Correct Answer - D |
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| 208. |
In ac circuit contains a pure capacitor, across which an ac emf `e = 100 sin (1000t)`, volt is applied. If the peak value of the current is 200 mA, then the value of the capacitor isA. `2mu`B. `20 muF`C. `5 muF`D. `500 muF` |
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Answer» Correct Answer - A |
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| 209. |
The voltage of an AC source varies with time according to the relation: ` E = 120 sin 100 pi t cos 100 pi t V`. What is the peak voltage of the source?A. `60` volt `100` HzB. `(120)/(sqrt(2))` volt, `100` HzC. `120` volt, `100` HzD. `60` volt, `200` Hz |
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Answer» Correct Answer - A |
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| 210. |
A thin semicircular conducting ring of radius R is falling with its plane vertical in a horizontal magnetic induction Vector B. At the position MNQ, the speed of the ring is v. The potential difference developed across the ring is(a) zero (b) 1/2 BvπR2, and M is at a higher potential (c) πRBv, and Q is at a higher potential (d) 2RBv, and Q is at a higher potential |
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Answer» Correct Answer is: (d) 2RBv, and Q is at a higher potential |
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| 211. |
According to Faraday’s law the induced emf produced in a closed loop is equal to the ……………. A) magnetic flux B) change of magnetic flux C) rate of change of magnetic flux D) cross – sectional area of the loop. |
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Answer» C) rate of change of magnetic flux |
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| 212. |
A conductor of 1 m length is moving with a speed of 10 m/s in the direction perpendicular to the direction of magnetic field of induction 0.8T. The induced e.m.f between the ends of the conductor is ……………………. A) 10 V B) 1 V C) 2 V D) 8 V |
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Answer» Correct option is D) 8 V |
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| 213. |
A conductor is moving with a speed of 10 nVs perpendicular to the direction of magnetic field of induction 0.5 T. If the induced emf is 5 V then the length of the conductor is ……………………. A) 0.25 m B) 0.01 m C) 4 m D) 1 m |
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Answer» Correct option is D) 1 m |
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| 214. |
No force works on the conductor carrying electric current when it is kept …………………. A) away from magnetic field B) in the magnetic field C) perpendicular to magnetic field D) parallel to magnetic field |
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Answer» D) parallel to magnetic field |
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| 215. |
What is Main Fuse? |
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Answer» Main Fuse: The live wire coming out from the output terminals or KWH meter has another fuse which is called the main fuse. |
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| 216. |
What is the magnetic force on the charge moving parallel to a magnetic field? |
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Answer» When the charge moves parallel to the magnetic field the value of “θ” becomes zero. In the equation F = qvB sin θ, since θ = θ, the value of force F also becomes zero. |
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| 217. |
Can we calculate the force experienced by a charge moving in a magnetic field? |
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Answer» Yes, If the force is F, it is given by the expression F = qvB. |
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| 218. |
Three indential rings move with same speed on a horizontal magnetic field normal to plane of rings. The first (a) slips without rolling, the second(b) rolls without slipping and the third rolls with slipping:A. The same emf is induced in all three ringsB. No emf is induced in any of the ringsC. In each ring all points are at the same potential.D. `B` develops the maximum induced emf and `A` the least |
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Answer» Correct Answer - A |
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| 219. |
What is Induced current? |
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Answer» Induced current: Whenever there is a continuous change of magnetic flux linked with the closed coil, the current is generated in the coil. This is known as induced current. |
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| 220. |
Can we generalize the equation for magnetic force on charge when there is an angle ‘0’ between the directions of field “B” and velocity “v”? |
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Answer» No, Then force F is given by the formula F = qvB sin θ. |
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| 221. |
Which type of material is used to make electric fuse? |
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Answer» An electric fuse is made of a material of low melting point. |
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| 222. |
Define the term Slip rings. |
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Answer» Slip rings: The reverse of current in an AC dynamo occurs because the two ends of the armature coil are in permanent contact with the same two slip rings and S2 |
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| 223. |
The general formula of the flux for any orientation of the plane taken in the field A) Φ = BAB) Φ = BA cos θ C) Φ = BA sin θ D) zero |
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Answer» B) Φ = BA cos θ |
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| 224. |
What is Magnetic flux? |
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Answer» Magnetic flux: The number of lines passing through the plane of area perpendicular to the field is called magnetic flux. It is denoted by ‘Φ’. Its SI unit is Weber. |
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| 225. |
Can we generalize the formula of flux for any orientation of the plane taken in the field? |
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Answer» Yes, Φ = BA cos θ |
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| 226. |
What is Electric motor? |
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Answer» Electric motor: It is a device which converts electrical energy into mechanical energy. |
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| 227. |
The S.I unit of magnetic flux is ……………….. A) Weber B) Weber/meter2 C) Tesla D) Both B and C |
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Answer» Correct option is A) Weber |
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| 228. |
Define the Magnetic flux density. |
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Answer» Magnetic flux density: Magnetic flux per unit area is known as magnetic flux density. This is also known as magnetic induction. ∴ B = \(\frac{ϕ}{A}\) Unit → Weber/metre2 or Tesla |
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| 229. |
What is magnetic flux density? |
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Answer» Magnetic flux density (B) is defined as the ratio of flux passing through a plane perpendicular to the field and the area of the plane. |
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| 230. |
What is the use of introducing the ideas of magnetic flux and magnetic flux density? |
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Answer» Magnetic flux and flux density help in understanding the concept of electromagnetic induction and relation between electricity and magnetism. |
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| 231. |
The S.I unit of magnetic flux density is...................A) Weber B) Weber/meter2 C) Telsa D) Both B and C |
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Answer» D) Both B and C |
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| 232. |
Magnetic flux density (B) = …………….. A) Area/Magnetic flux B) Length/Magnetic flux C) Magnetic flux/Length D) Magnetic flux/ Area |
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Answer» D) Magnetic flux/ Area |
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| 233. |
The magnetic field is called uniform if A) strength and direction of magnetic field are changing B) strength and direction of magnetic field are constant C) only magnetic field strength is constantD) only direction of magnetic field is constant |
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Answer» B) strength and direction of magnetic field are constant |
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| 234. |
How can you demagnetise a bar magnet by employing alternating current? |
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Answer» When current starts flowing in the coil and magnet is with drawn from the coil in East-West direction and is kept far away, the magnetic field produced changes its direction continously, magnetisation becomes weak and weak untill demagnetised. |
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| 235. |
The direction of lines of force in the inner side of a solenoid is …………………. A) North to south B) South to north C) East to west D) West to east |
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Answer» B) South to north |
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| 236. |
What is Lenz’s law? |
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Answer» Lenz’s law: The induced current set up in the coil is in such a direction that it opposes the changes in the flux. |
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| 237. |
Why are magnets with concave shaped poles used in a D.C. motor? What happens if magnets with flat poles are used in it ? |
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Answer» How do the magnetic lines of force passing through the magnetic field change as the shape of the magnet changes ? How do the magnetic lines forces pass through the magnetic field if the magnetic poles are flat ? How should the magnetic lines of force pass through a magnetic field to produced more turning effect in an armature ? |
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| 238. |
Can we give certain values to magnitude of the field at every point in the magnetic field? |
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Answer» In uniform magnetic field it is same whereas in non-uniform magnetic field it is different. |
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| 239. |
What is the use of Permanent magnets? |
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Answer» Permanent magnets are used in galvanometers, voltmeters, ammeters, speedometers, etc. |
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| 240. |
The equation for magnetic force on charge ‘q’ moving perpendicular to the magnetic field is A) F = Bqv B) F = Bqv sinθ C) F = Bqv cosθ D) zero |
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Answer» Correct option is A) F = Bqv |
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| 241. |
What is the flux through unit area perpendicular to the field? |
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Answer» Flux density or magnetic induction. |
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| 242. |
What is Faraday’s law? |
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Answer» Faraday’s law: The induced EMF generated in a closed loop is equal to the rate of change of magnetic flux passing through it. |
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| 243. |
If B is the magnetic flux density and A is the area of the plane then the magnetic flux is given by A) AB B) B/A C) A/BD) A2B |
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Answer» Correct option is A) AB |
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| 244. |
What are the use of electromagnets? |
Answer»
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| 245. |
What is the flux through the plane taken parallel to the field? |
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Answer» Magnetic flux (or) Magnetic field. |
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| 246. |
The flux through the plane taken perpendicular to the field is………………. A) Φ = BA B) Φ = BA cos θ C) Φ = BA sin θD) zero |
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Answer» Correct option is A) Φ = BA |
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| 247. |
In electric motor, electrical energy is converted into which type of energy? |
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Answer» In an electric motor, electrical energy is converted into mechanical energy. |
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| 248. |
The magnetic force on the charge ‘q’ moving parallel to the magnetic field is …………………… A) F = Bqv B) F = Bqv sinθ C) F = Bqv cosθ D) zero |
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Answer» Correct option is D) zero |
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| 249. |
What is Energy meter or KWH meter? |
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Answer» Energy meter or KWH meter: The cable connected to the energy meter records the electricity consumption of the house in kilowatt-hour. |
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| 250. |
Can you draw the direction of magnetic force on sides AB and CD? |
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Answer» Yes. The direction of magnetic force on sides AB and CD can be determined by applying right hand rule. |
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