12th class (Fsc) Physics unit 3 MCQs
26. For a current carrying solenoid the term “n” has units as:
a. m-2
b. No unit
c. m-3
d. m-1
27. 1 Tesla = ………:
a. 1NA-1 m2
b. N-1 Am
c. ANA-1 m-1
d. 1NAm2
28. The unit for permeability of free space is:
a. WbmA-1
b. WbA-1 m-1
c. WbAm-1
d. Wbm-2
29. The SI unit of flux density is:
a. NAm-1
b. Nm-1 A-2
c. NAsm
d. NA-1 m-1
30. Magnetic flux is minimum, when angle between vector area and B is:
a. 90o
b. 0o
c. 180o
d. 45o
31. A charged particle having charge q is moving at right angle to magnetic field. The quantity which varies is:
a. Path of motion
b. Speed
c. Angular velocity
d. Kinetic energy
32. When a charge is projected perpendicular to a uniform magnetic field, its path is:
a. Ellipse
b. Spiral
c. Circular
d. Helix
33. The value of shunt resistance is given by (R,):
a. l/l-lg
b. l-lg/lg
c. Vg/l-lg
d. l-Vg/lg
34. The Lorentz force on a charged particle moving in electric field E and magnetic field B is given by:
a. F = FB/FE
b. F = FE+FB
c. F = FEXFB
d. F = FE-FB
35. Lorentz force is given by:
a. q[→E x (→V + →B) ]
b. q (→E –→V x →B )
c. q (→V +→E x →B )
d. q (→E +→V x →B )
36. Shunt resistance is:
a. Zero resistance
b. Low resistance
c. Impedence
d. High resistance
37. The value of shunt resistance is given by (Rs):
a. lRg/ l – lg
b. l – lo/ lg
c. Vg/ l- lg
d. l – Vo/ lg
38. If a charge is at rest in a magnetic field then force on charge is:
a. qVB sinΦ
b. Zero
c. QVB cosΦ
d. q (→V X → B)
39. Write the SI unit of magnetic flux:
a. Nm-1 A-1
b. N.mA-1
c. Nma
d. Nm-1 A
40. The unit of magnetic flux is:
a. weber m-2
b. Tesla
c. Tesla m-2
d. Weber
41. The unit of ENC-1 and that of B is NA-1m-1 then the unit of E/B is:
a. ms-1
b. ms-2
c. m-1 s-1
d. Ms
42. The value of e/m is smallest for:
a. β– Particle
b. Proton
c. Positron
d. Electron
43. The field inside a solenoid is given by:
a. µonl2
b. µonl
c. µoNl
d. µon2l
44. The value of permeability of free space in SI unit is:
a. 4𝝅 x 10-10 WbA-1
b. 4𝝅 x 107 WbA-1
c. 4𝝅 x 109 WbA-1
d. 4𝝅 x 10-7 WbA-1
45. If the number of turns become double but length remain same, then magnetic field in the solenoid become:
a. Remain same
b. Half
c. Zero
d. Double
46. Energy stored per unit volume inside a solenoid is called as:
a. Work
b. Energy density
c. Volume charge density
d. Electric flux
47. The magnetic-force on an electron travelling with velocity 108ms-1 perpendicular to magnetic field of strength 1Wb.m-2 :
a. 5 x 10-11N
b. 2 x 10-11N
c. Zero
d. 1.6 X 10-11N
48. If the length and number of turns of a solenoid are doubled strength of magnetic field will:
a. Not change
b. Be doubled
c. Be four time
d. Become half
49. Magnetic flux density is measured in:
a. Tesla-m
b. Weber
c. Gauss
d. Weber / m2
50. The S.I unit of magnetic induction is:
a. Gauss
b. Weber
c. Newton
d. Tesla