12th class (Fsc) Physics unit 4 MCQs
26. The mutual inductance of the coils depends upon:
a. Material of coils
b. Stiffness of the coils
c. Geometry of the coils
d. Density of the coils
27. The winding of the electromagnet in motor are usually called:
a. Electric coils
b. Magnetic coils
c. Electric-o-electric coils
d. Field coils
28. ……… expressions for mutual inductance is correct.
a. M = lp/ Nsfs
b. M = NsΦs/lp
c. M = Ns/ lpfs
d. M = Φs/Nslp
29. The mutual inductance between two coils depends upon their:
a. Separation
b. Size
c. Size, core material and separation
d. Core material
30. The inductance can be increased by winding the wire around a core made of:
a. Iron
b. Copper
c. Aluminum
d. Silicon
31. The application of mutual induction is a:
a. Television
b. D.C motor
c. Transformer
d. Radio
32. EMF is induced due to change in:
a. Magnetic flux
b. Charge
c. Electric field
d. Current
33. Mutual induction play role in:
a. Galvanometer
b. Generator
c. Transformer
d. D.C motor
34. Self-inductance does depend upon:
a. Nature of core material
b. Number of turns of the coil
c. Current through inductor
d. Area of cross section of coil
35. Self-induction does not depend on:
a. Nature of material of the core
b. Number of turns of the coil
c. Energy stored in an inductor
d. Area of cross section of the core
36. By winding the cold around a fess magnetic core, self-induction:
a. Remain same
b. Will increase
c. First increase then decrease
d. Will decrease
37. The self-induction is given by:
a. NΦ = LI
b. NL = ΦI
c. N = LI
d. NI = ΦI
38. Unit of self-inductance is:
a. Henry
b. Weber
c. Farad
d. Tesla
39. The self-induction emf is sometimes called:
a. Back emf
b. Motional emf
c. Variable emf
d. Constant emf
40. The self-inductance of solenoid is:
a. L = µon2Al
b. L = µonAl
c. L = µoNAL
d. L = µoN2Al
41. Energy stored in inductor is:
a. 1/2 L2 l
b. 1/2 Ll2
c. 1/2 L2 l2
d. 1/2 Ll
42. If magnetic field is doubled then magnetic energy density becomes:
a. Three times
b. Four times
c. Six times
d. Two times
43. In case of inductor, energy is stored in the:
a. Potential field
b. Electric field
c. Gravitational field
d. Magnetic field
44. Energy density in an inductor is:
a. Inversely proportional to magnetic field
b. Directly proportional to magnetic field
c. Inversely proportional to square of magnetic field
d. Directly proportional to square of magnetic field
45. Energy stored per unit volume is called:
a. Energy density
b. Surface charge density
c. Induction
d. Power density
46. A 50 mH coil caries a current 2.0 A. then energy stored in its magnetic field is:
a. 100 J
b. 0.1 J
c. 1000 J
d. 10 J
47. B2/2µo is the expression of:
a. Magnetic energy density
b. Lenz’s Law
c. Back emf
d. Magnetic energy
48. The energy stored in the inductor per unit volume is:
a. µo/2B2
b. B2/2µo2
c. B2/2µo
d. µo/2B
49. Energy density in inductor is given by:
a. 1/2 B2/µo
b. 1/2 B/µo
c. 1/2 B2/µo2
d. 1/2 B/µo2
50. The equation for energy density is given as:
a. 1/2 B/µo2
b. 1/2 B2/µo
c. 1/2 B/µo
d. 1/2 B2/µo2