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InterviewSolution
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.
| 251. |
Why electrical energy is transmitted at high voltage and low current ? |
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Answer» (i) `P prop i^(2)` (ii) Heat energy `prop i` |
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| 252. |
What type of current is transmitted from the power station? |
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Answer» An alternating current is transmitted from the power station. |
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| 253. |
Name the transformer used in the power transmitting station of a power plant. |
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Answer» A step-up transformer is used in the power transmitting station of a power plant. |
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| 254. |
State two dissimilarities between a d c motor and an a.c. generator. |
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Answer» Different between D.C. motor and A.C. generator D.C. Motor 1. It converts electrical energy to mechanical 2. It is based on Fleming’s left hand rule energy. 3. It has split rings. 4. DC motor works on the principle of force acting on current carrying conductor placed in a magnetic field. A.C. Generator 1. It converts mechanical energy to electrical energy. 2. It is based on Fleming’s right hand rule. 3. It has slip rings. 4. AC generation works on the principle of electromagnetic induction |
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| 255. |
State two factors on which the strength of an induced current depends. |
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Answer» Two factors on which strength of induced current depends are: (a) The magnitude of current is directly proportional to “The rate of change of magnetic flux with in the closed coil. (b) It depends upon the number of turns and the area of cross-section of the coil. |
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| 256. |
State one point of similarity and one point of difference between an a.c. generator and a d.c. motor. |
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Answer» Answer: Difference between a.c. generator and d.c. motor In a.c. generator mechanical energy gets converted into electrical energy and induced e.m.f. is alternating in nature. In d.c. motor electrical energy gets converted into mechanical energy and electricity used in direct current. Similarity between a.c. generator and d.c. motor is that both use the principle of electromagnetic induction and use a solenoid on which copper wire is would. |
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| 257. |
When a solenoid that is carrying current is freely suspended, it comes to rest along a particular direction. Why does this happen? |
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Answer» This means the solenoid carrying current behaves like a bar magnet and it has come to rest along a particular direction N S N-end of this solenoid points towards north pole of earth and S-end points towards south-pole of earth. |
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| 258. |
Why does a current carrying freely suspended solenoid rest along a particular direction? |
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Answer» A current carrying solenoid behaves like a bar magnet. |
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| 259. |
Distinguish between AC and DC. |
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Answer»
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| 260. |
Distinguish between AC motor and DC motor. |
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Answer»
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| 261. |
Give two similartyies between an Ac generation and DC motor. |
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Answer» Two similarities between an AC generator and a DC motor are
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| 262. |
In an electric motor : (a) mechanical energy changes to heat energy (b) mechanical energy changes to electric energy (c) electric energy changes to mechanical energy. (d) electric energy changes to magnetic energy. |
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Answer» (c) electric energy changes to mechanical energy. |
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| 263. |
By reversing the direction of current in an electromagnet, the magnetic field produced by it (a) increases in strength (b) remains unchanged in strength and direction (c) gets reversed in direction (d) decreases in strength |
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Answer» (c) gets reversed in direction |
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| 264. |
fill in the blanks on reversing the direction of the current in a wire the magnetic field produced by its gets…….. |
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Answer» On reversing the direction of the current in a wire, the magnetic field produced by it gets reversed. |
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| 265. |
Two bulbs `100 W, 250 V` and `200 W, 250 V` are connected in parallel across a `500 V` line. Then-A. `100 W` bulb with fusedB. 200 W bulb will fusedC. Both bulbs will be fusedD. No bulb will fused |
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Answer» Correct Answer - C |
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| 266. |
A long resistance wire is divided into 2n parts. Then n parts are connected in series and the other n parts in parallel separately. Both combinations are connected to identical supplies. Then the ratio of heat produced in series to parallel combinations will be -A. `1 : 1`B. `1 : n^(2)`C. `1 : n^(4)`D. `n^(2) : 1` |
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Answer» Correct Answer - C |
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| 267. |
Two point charges `Q` and `-3Q` are placed at some distance apart. If the electric field at the location of `Q` is `E` then at the locality of `-3Q`, it isA. `3vecE`B. `-3vecE`C. `vecE//3`D. `-vecE//3` |
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Answer» Correct Answer - C |
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| 268. |
Which coil of a step up transformer is made thicker and why? |
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Answer» The primary coil of step up transformer is made thicker. it is because a current of higher magnitude flows in this coil, which in turn made melt it on account of resistance. Thus, in order to lower resistance it is made thicker. |
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| 269. |
A hemisphere (radius R) is placed in electric field as shown in fig. Total outgoing flux is - A. `piR^(2)E`B. `2piR^(2)E`C. `4piR^(2)E`D. `(piR^(2)E)//2` |
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Answer» Correct Answer - A |
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| 270. |
In the previous question which lamp will glow more brightly when they are in connected in series ?A. Lamp having lower resistanceB. Lamp having higher resistanceC. Both the lampsD. None of the two lamps |
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Answer» Correct Answer - A |
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| 271. |
In previous question if the particles started from rest and all are positively charge which particles must have been acted upon by a force other than that produced by the electric field.A. W and YB. X and ZC. X,Y and ZD. W, X,Y and Z |
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Answer» Correct Answer - C |
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| 272. |
In the diagram (given below) the broken lines represent the paths followed by particles W,X, Y and Z respectively through the constant field E. The numbers below the field represents meters. `` If the particles begin and end at rest, and all are positively charged, the same amount of work was done on which particles.A. W and ZB. W, Y and ZC. Y and ZD. W, X, Y and Z |
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Answer» Correct Answer - C |
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| 273. |
Two equal positive charges are kept at points A and B. The electric potential at the points between A and B (exculding these points ) is studid while moving from A to b. The potentialA. Continuously increasesB. Continuously decreasesC. Increases then decreasesD. Decreases then increases |
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Answer» Correct Answer - D |
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| 274. |
You have been provided with a solenoid AB. 1. What is the polarity at end A? 2. Give one advantage of an electromagnet over a permanent magnet. |
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Answer» 1. Polarity at the end A is NORTH pole . 2. An electromagnet’s strength can be increased by increasing the flow of current in the coil, which is not possible in case of a permanent magnet. |
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| 275. |
The scientist who discovered the magnetic effect of current: A) Oersted B) Faraday C) Ampere D) Fleming |
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Answer» Correct option is A) Oersted |
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| 276. |
Which of the following statements is correct ?A) A current carrying circular wire behaves like a thin disc magnetB) If the current flows around the face of a circular coil in the clock-wise direction that face of the circular wire will be south pole. C) If the current flows around the face of a circular coil in the anti clock-wise direction that face of the circular wire will be north pole. D) All of the above |
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Answer» D) All of the above |
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| 277. |
State the Lenz’s principle. |
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Answer» The induced current will appear in such a direction that it opposes the changes in the flux in the coil. |
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| 278. |
What do you mean by magnetic effect of current? |
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Answer» Current carrying conductor produces a magnetic field around it. This is called magnetic effect of current. |
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| 279. |
Statement X: The direction of the magnetic field due to circular coil points to wards you when the current in the coil is in anti clock wise direction. Statement Y : The direction of the magnetic field due to circular coil points away from you when the current in the coil is . clock wise direction. A) Both statements are true B) Both statements are false C) X is true, Y is false D) X is false, Y is true |
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Answer» A) Both statements are true |
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| 280. |
Which of the following diagram represents the direction of magnetic field lines produced by a straight conductor when an electric current flows in up ward direction i.e out of the page? |
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Answer» Correct option is D) |
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| 281. |
What is induced emf? |
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Answer» Change in magnetic flux produces emf in the circuit called induced emf. |
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| 282. |
Statement X : Magnetic flux represents the number of lines passing through the plane in the field. Statement Y : The magnetic flux depends on the orientation of the plane in the field.A) Both statements are true B) Both statements are falseC) X is true, Y is false. D) X is false, Y is true |
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Answer» A) Both statements are true |
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| 283. |
How induced emf can be increased? |
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Answer» If the number of turns, area, speed of the rotation of armature increases induced emf is increased. |
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| 284. |
The given figure represents . A) DC B) AC C) both A and BD) none |
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Answer» Correct option is A) DC |
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| 285. |
What is motional EMF? |
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Answer» When a conductor of length ‘V moves perpendicular to field B with a speed v then the potential difference (voltage) developed between the ends of the conductor is B/v. This EMF is called motional EMF. |
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| 286. |
The number of lines passing through the plane of area perpendicular to the field is called A) magnetic field B) magnetic fluxC) magnetic flux densityD) none |
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Answer» B) magnetic flux |
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| 287. |
Which of the following statements is correct ? A) The magnetic field produced by a bar magnet-is non-uniform.B) The magnetic field produced by a bar magnet is uniform. C) Earth’s magnetic field is uniform. D) Earth’s magnetic field is non¬uniform. |
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Answer» C) Earth’s magnetic field is uniform. |
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| 288. |
Statement X : If the field strength or direction of field change from point to point then the field is said to be non-uniform. Statement Y : If both field strength and direction of field are constant throughout the field then the field, is said to be uniform. A) Both statements are true B) Both statements are false C) X is true, Y is falseD) X is false, Y is true |
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Answer» A) Both statements are true |
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| 289. |
Statement X : The magnetic field is strong when lines are crowded. Statement Y : The magnetic field is weak when lines are spaced apart. A) Both statements are true B) Both statements are false C) X is true, Y is false D) X is false, Y is true |
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Answer» A) Both statements are true |
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| 290. |
The observation made of Faraday from the experiments on electromagnetic induction is (are) that ________. (A) the deflection in the galvanometer increases when a strong magnet is used (B) the induced current in the coil is alternating in natureA. Only A is trueB. Only B is trueC. Both A and B are trueD. Both A and B are false |
| Answer» Correct Answer - C | |
| 291. |
Which of the following statement is true ?A) A magnetic field is characterized by strength and direction. B) The direction of the magnetic field can be determined by using a compass. C) The strength of the magnetic field varies with distance from the bar magnet. D) all of the above |
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Answer» D) all of the above |
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| 292. |
The strength of magnetic field due to a straight current carrying conductor, at a given distance increases with increase in theA. temperature of the conductorB. length conductorC. strength of the currentD. Both (a) and (c) |
| Answer» Correct Answer - C | |
| 293. |
The magnetic field around a magnet is A) one dimensionalB) two dimensional C) three dimensional D) none |
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Answer» C) three dimensional |
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| 294. |
A conductor of length of 1m moving with velocity ‘v’ perpendicular to the magnetic field of strength 10 Tesla induces an e.m.f of 10 volts. Then v = ………….. m/s A) 100 B) 10 C) 1 D) 0.1 |
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Answer» Correct option is C) 1 |
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| 295. |
The unit of magnetic field strength is A) Oersted B) Ampere C) Coloumb D) Faraday |
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Answer» Correct option is A) Oersted |
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| 296. |
An ac circuit contains a resistance R and a reactance X. If the impedace of the circuit is given by `Z = 50 anglepi//6` Then the resistance and the reactance are, respectively (in ohms) –A. Zero `, 50`B. `25sqrt(3) , 25`C. `25 , 25sqrt(3)`D. `25 , 25` |
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Answer» Correct Answer - B |
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| 297. |
A long straight wire carries the current along +ve x-direction. Consider four points in space `A(0,1,0), B(0,1,1), C(1,0,1), and D(1,1,1)`. Which of the pairs will have the same magnitude of magnetic field?A. `A` and `B`B. `A` and `C`C. `B` and `C`D. `B` and `D` |
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Answer» Correct Answer - B::D |
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| 298. |
In an AC circuit, the reactance is equal to the resistance. The power factor of the circuit will be (a) 1 (b) 1/2 (c) 1/√2 (d) zero |
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Answer» Correct Answer is: (c) 1/√2 tan φ = X/R = 1. Power factor = cos φ = 1/√2. |
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| 299. |
An observer A and a charge Q are fixed in a stationary frame F1. An observer B is fixed in a frame F2, which is moving with respect to F1. (a) Both A and B will observe electric fields. (b) Both A and B will observe magnetic fields. (c) Neither A nor B will observe magnetic fields. (d) B will observe a magnetic field, but A will not. |
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Answer» Correct Answer is: (a, d) |
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| 300. |
An observer `A` and `a` charge `Q` are fixed in a stationary frame `F_(1)`. An observer `B` is fixed in a frame `F_(2)` which is moving with respect to `F_(1)`A. Both `A` and `B` will observe electric fields.B. Both `A` and `B` will observe magnetic fields.C. Neigher `A` nor `B` wil observe magnetic fields.D. `B` will observe a magnetic field, but `A` will not. |
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Answer» Correct Answer - A::D |
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