Materials and Components – Section 2
42. | A piece of iron is placed in a magnetic field | |||||||
Answer: Option B |
43. | Assertion (A): Magnetism can be explained by the theory of magnetic domains.
Reason (R): The existence of magnetic domains is evident from the Bitter powder patterns. |
|||||||
Answer: Option B |
44. | Ferromagnetic materials | |||||||
Answer: Option D |
45. | In a specimen of ferromagnetic material, as the flux density is increased from zero to 2.5 T, µr will | |||||||
Answer: Option D |
46. | Assertion (A): Relaxation time and mean time between collisions are equal when scattering is isotropic.
Reason (R): Mean free path of an electron λ, velocity of electron v and mean time between collisions tc are related as λ = vTc. |
|||||||
Answer: Option B |
47. | Assertion (A): Copper is a monoatomic solid.
Reason (R): In a metal the valence electrons belong to all atoms. |
|||||||
Answer: Option B |
48. | The heat developed per m3 per second (W) in a conductor having a conductivity σ and a field E is | |||||||
Answer: Option A |
49. | The number of valence electrons in acceptor impurity are | |||||||
Answer: Option C |
50. | If q is charge on an electron, R is radius of electron orbit and ω is angular velocity of electron rotation, the magnetic dipole moment of electron in orbit is | |||||||
Answer: Option C |