12th class (Fsc) Physics unit 4 MCQs
chapter 4 MCQs 12th Class Physics
Electromagnetic Induction:
1. If we make magnetic field stronger the value of induced current is:
a. Vanishes
b. Decreased
c. Remains constant
d. Increased
2. When a conductor moves across a magnetic field, an emf is set up, this emf is called:
a. Back emf
b. Variable emf
c. induced emf
d. Constant emf
3. The motional emf developed in a conductor depends upon:
a. Magnetic field
b. Length
c. Orientation
d. All of the above
4. If 10A current passes through 100 mH incutor, then energy stored as:
a. 20J
b. 100J
c. Zero
d. 5J
5. The rod of unit length is moving at 30o through a magnetic field of 1 T. If the velocity of rod is 1 m/s, then induced emf in the rod will be given by:
a. 0.5V
b. 1V
c. 0.6V
d. 0.25V
6. A metal rod of 1m is moving at a speed of 1ms in a direction making an angle 30o with 0.5T magnetic field. The emf produced is:
a. 0.25 N
b. 0.25 N
c. 2.5 N
d. 2.5 N
7. When a coil is moved in a uniform magnetic field, an induced emf is produced due to change in:
a. Magnetic flux
b. Flux density
c. Magnetic field strength
d. Electric flux
8. Henry is SI unit of:
a. Flux
b. Current
c. Self-induction
d. Resistance
9. If the coil is wound on iron core, the flux through it:
a. Increases
b. Decreases
c. Remains constant
d. Becomes zero
10. Induced emf can be increased by:
a. Increasing number of turns of coil
b. Increasing resistance of the coil
c. Decreasing number of turns of coil
d. Decreasing resistance of the coil
11. One Tesla is equal to:
a. Nm-1A-1
b. NmA-1
c. Nam
d. N-1mA
12. The device which allows only the flow of D.C is:
a. Inductor
b. Capacitor
c. Generator
d. Transformer
13. SI unit of hennery which is:
a. VS-1A-1
b. VSA-1
c. VSA
d. VS-1A
14. The motional emf depends upon the:
a. Strength of magnet
b. Length of conductor
c. Speed of conductor
d. All of above
15. The relation of EMF of two cell E1/E2 is:
a. 1/ l1 l2
b. l2 / l1
c. l1 x l2
d. l1 / l2
16. The motional emf is given by:
a. eBL
b. qUB
c. VBL
d. IBL
17. One henry is equal to:
a. V-1 ,s.A
b. VsA-1
c. Ns,Np=1
d. N.mA-1
18. The negative sign with induced emf in Faraday’s Law is in accordance is in:
a. Gauss Law
b. Lenz’s Law
c. Boyle’s Law
d. Ampere’s Law
19. Lenz’s Law is in accordance with the law of conservation of:
a. Energy
b. Momentum
c. Angular momentum
d. Charge
20. Lenz’s Law deals with:
a. Direction of induced current
b. Magnitude of emf
c. Resistance
d. Direction of emf
21. Electromagnetic induction obeys law of conservation of:
a. Momentum
b. Charge
c. Mass
d. Energy
22. Lenz’s Law is a consequence of the Law of conservation of:
a. Energy
b. Charge
c. Momentum
d. Current
23. The Lenz’s Law fulfills:
a. Law of conservation of momentum
b. Law of conservation of energy
c. Kirchhoff’s Law
d. Law of conservation of charge
24. A positive charge is mobbing towards an observer. The direction of magnetic induction will be:
a. Anti-clock wise
b. Towards right
c. Towards left
d. Clock wise
25. Mutual induction has a practical role in the performance of the:
a. A.C Generator
b. Transformer
c. D.C Generator
d. Radio choke