MCQOPTIONS
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MCQOPTIONS
This section includes 36 Mcqs, each offering curated multiple-choice questions to sharpen your Physics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
cmf generated by A.C dynamo depends upon |
| A. | Number of turns in the coil |
| B. | Magnetic field strength |
| C. | Frequency of rotation |
| D. | All of above |
| Answer» E. | |
| 2. |
An aeroplane of wingspan 10m flies from the equator towards the North Pole. The wings are perpendicular to the vertical component of the earths magnetic field (B = 4 10-5T). At maximum speed an emf of 96mV is induced across the wing tips. The maximum speed of the aeroplane is |
| A. | 150msec-1 |
| B. | 384msec-1 |
| C. | 38.4msec-1 |
| D. | 200msec-1 |
| Answer» C. 38.4msec-1 | |
| 3. |
For electroplating we use |
| A. | A D.C source |
| B. | An A.C source |
| C. | Any source |
| D. | All of the above |
| Answer» B. An A.C source | |
| 4. |
Energy stored in a magnetic field is given by |
| A. | LI2 |
| B. | L2I/2 |
| C. | LI2/2 |
| D. | IL2 |
| Answer» D. IL2 | |
| 5. |
An electric current induced within the body of a conductor when that conductor either moves through a non uniform magnetic field or in a region where there is a change in magnetic flux is called |
| A. | Induced current |
| B. | Eddy current |
| C. | Back emf |
| D. | None of the above |
| Answer» C. Back emf | |
| 6. |
A coil of wire is arranged with its plan perpendicular to a uniform magnetic field o flux density B. when the radius of the coil increases from r1 to r2 in time ?t then what is the emf induced in the coil? |
| A. | ?B/r22-r12/?t |
| B. | ?B(r2-r1)2/?t |
| C. | ?B(r22-r12)/?t |
| D. | ?B(r22+r12)/?t |
| Answer» D. ?B(r22+r12)/?t | |
| 7. |
A metal rod of 25 cm length is moving at a speed of 0.5/sec in direction perpendicular to 0.25T magnetic field. Emf produced in the rod is |
| A. | 0 volt |
| B. | 3.125 volt |
| C. | 31.25 volt |
| D. | 0.03125 volt |
| Answer» E. | |
| 8. |
A small coil lies inside a large coil. The two coils are horizontal concentric and carry currents in opposite directions. The large coil will experience |
| A. | A torque about horizontal axis |
| B. | A torque about vertical axis |
| C. | An upward force along the axis |
| D. | No resultant force |
| Answer» E. | |
| 9. |
A.C can not be used for |
| A. | Producing heat |
| B. | Producing light |
| C. | Magnetizing iron |
| D. | Producing magnetic field |
| Answer» D. Producing magnetic field | |
| 10. |
A.C and D.C have the same |
| A. | Effect in charging a capacitor |
| B. | Effect in charging a battery |
| C. | Effect while passing through an inductance |
| D. | Heating effect through a resistance |
| Answer» E. | |
| 11. |
A.C cannot be used for |
| A. | Producing heat |
| B. | Producing light |
| C. | Magnetizing and electroplating |
| D. | All the above |
| Answer» D. All the above | |
| 12. |
Current produced by moving the loop of wire across a magnetic field is called |
| A. | A.C current |
| B. | D.C current |
| C. | Induced current |
| D. | Mean square current |
| Answer» D. Mean square current | |
| 13. |
emf induced in a circuit according to Faradays law depends on the |
| A. | Maximum magnetic flux |
| B. | Rate of change of magnetic flux |
| C. | Change in magnetic flux |
| D. | Initial magnetic flux |
| Answer» C. Change in magnetic flux | |
| 14. |
The out put voltage of a transformer is 3 times the input voltage then turns ratio will be |
| A. | 3-Jan |
| B. | 3 |
| C. | 1 |
| D. | 6 |
| Answer» C. 1 | |
| 15. |
The practical illustration of the phenomenon of mutual induction is |
| A. | A.C generator |
| B. | D.C dynamo |
| C. | Induction coil |
| D. | Transformer |
| Answer» E. | |
| 16. |
The self-inductance of a solenoid is increased when a soft iron core is inserted into it. This is because the soft iron core |
| A. | Decreases the resistance of the solenoid |
| B. | Reduces the effect of eddy current |
| C. | Improves the flux linkage between the turns of the coil |
| D. | Increases the mutual inductance between the solenoid and the core |
| Answer» D. Increases the mutual inductance between the solenoid and the core | |
| 17. |
Weber is the unit of |
| A. | Magnetic field intensity |
| B. | Magnetic induction |
| C. | Magnetic flux |
| D. | Self-inductance |
| Answer» D. Self-inductance | |
| 18. |
When the motor is at its maximum speed then back emf will be |
| A. | Maximum |
| B. | Zero |
| C. | Intermediate values |
| D. | No back emf |
| Answer» B. Zero | |
| 19. |
Which of the following uses electric energy and does not convert it into any other form? |
| A. | Transformer |
| B. | Motor |
| C. | D.C generator |
| D. | A.C generator |
| Answer» B. Motor | |
| 20. |
Lagging of changes in the magnetization of a substance behind changes in the magnetic field as the magnetic field is varied is known as magnetic |
| A. | Retaintivity |
| B. | Permeability |
| C. | Flux |
| D. | Hysteresis |
| Answer» E. | |
| 21. |
Which of the following works on torque on the current carrying conductor placed in magnetic field. |
| A. | Galvanometer |
| B. | Ammeter |
| C. | Voltmeter |
| D. | All of the above |
| Answer» E. | |
| 22. |
Which one of the following devices does not function like an electric motor? |
| A. | Galvanometer |
| B. | Ammeter |
| C. | Voltmeter |
| D. | Transformer |
| Answer» E. | |
| 23. |
Which one of the following functions like a motor? |
| A. | Galvanometer |
| B. | Ammeter |
| C. | Voltmeter |
| D. | All of above |
| Answer» E. | |
| 24. |
For long distance transmission the transformer used is |
| A. | Step down |
| B. | Input voltage and output voltage remain same |
| C. | Step up |
| D. | Amplifier is used |
| Answer» D. Amplifier is used | |
| 25. |
If the coil is wound on an iron core the flux through it will |
| A. | Decrease |
| B. | Become zero |
| C. | Remain the same |
| D. | Increase |
| Answer» E. | |
| 26. |
If the secondary coil has Ns turns and the primary Np turns the relation between secondary and primary voltages is given by |
| A. | Vs/Vp = Np/Ns |
| B. | Vs/Vp = Ns/Np |
| C. | Vp/Vs = Ns/Np |
| D. | Vp/Vs = Np/Ns |
| Answer» C. Vp/Vs = Ns/Np | |
| 27. |
Inductors acts as a short circuit for |
| A. | AC |
| B. | DC |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 28. |
Long distance transmission is easy for |
| A. | D.C voltage |
| B. | A.C voltage |
| C. | Half A.C voltage |
| D. | Half D.C voltage |
| Answer» C. Half A.C voltage | |
| 29. |
Magnetic compass needle will be deflecting if it is kept near |
| A. | Static charge |
| B. | Soft iron |
| C. | Semi-conductor |
| D. | Accelerating charge |
| Answer» E. | |
| 30. |
Non inductive resistances are used in decreasing |
| A. | Mutual inductance |
| B. | Self inductance |
| C. | Magnetic fields |
| D. | Heating effect |
| Answer» C. Magnetic fields | |
| 31. |
Power loss in actual transformer is due to |
| A. | Small output |
| B. | Eddy currents and magnetic hysterias |
| C. | Soft iron core |
| D. | Back emf |
| Answer» C. Soft iron core | |
| 32. |
Self inductance of a coil depends upon |
| A. | Current flowing |
| B. | Number of turns per unit length |
| C. | Voltage produce |
| D. | All |
| Answer» E. | |
| 33. |
Self inductance of a long solenoid is |
| A. | ??n2?A |
| B. | ??n2A/? |
| C. | ??N2?A |
| D. | BA |
| Answer» B. ??n2A/? | |
| 34. |
The alternating current has frequency of 106 Hz in such a way that time period for completion of cycle is |
| A. | 1?s |
| B. | 1.5?s |
| C. | 106sec |
| D. | 1sec |
| Answer» B. 1.5?s | |
| 35. |
The emf induced in a conductor of unit length moving with unit velocity at right angles to a magnetic field is equal to |
| A. | Magnetic flux density |
| B. | Torque |
| C. | Mutual induction |
| D. | Motional emf |
| Answer» B. Torque | |
| 36. |
The only difference between construction of D.C generator and A.C generator is that of |
| A. | Carbon brushes |
| B. | Coil |
| C. | Commutator |
| D. | Magnetic field |
| Answer» D. Magnetic field | |