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Materials and Components – Section 4(Page 5)

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Materials and Components – Section 4

41.  In a virgin specimen of iron, the direction of spontaneous magnetisation varies from domain to domain.
A. True
B. False

Answer: Option A
42.  Which of the following is used in lightning arresters?
A. Thermistor
B. Photoconductor
C. Transistor
D. Varistor

Answer: Option D
43.  High frequency inductors and capacitors are commonly plated with silver. The main purpose of this is to
A. reduce dc resistance
B. reduce ac resistance
C. increase dc resistance
D. increase ac resistance

Answer: Option B
44.  In its lowest state, the electron is bound to the field of proton by an energy equal to
A. 100.5 eV
B. 51.2 eV
C. 13.6 eV
D. 0.2 eV

Answer: Option C

Explanation:

13.6 eV is required to ionize hydrogen atom.
45.  In a ferromagnetic material, the internal field seen by a dipole is
A. equal to applied field
B. equal to applied field minus a contribution from neighbouring dipoles
C. equal to applied field plus a contribution from neighbouring dipoles
D. equal to or less than applied field

Answer: Option C
46.  The iron core of a coil is removed so that it becomes an air cored coil. Its inductance will
A. increase
B. decrease
C. remain the same
D. may increase or decrease

Answer: Option B

Explanation:

Because magnetic flux will decrease.
46.  The iron core of a coil is removed so that it becomes an air cored coil. Its inductance will
A. increase
B. decrease
C. remain the same
D. may increase or decrease

Answer: Option B

Explanation:

Because magnetic flux will decrease.
48.  In an hydrogen atom, an electron moves in the field of a proton. The stability of orbit requires equilibrium between coulomb’s force and centrifugal force.
A. True
B. False

Answer: Option A

Explanation:

Orbit is stable only if the two forces are equal and opposite.
49.  For small size high frequency coils, the most common core material is
A. air
B. ferrite
C. powdered iron
D. steel

Answer: Option A
50.  The orientation polarization of a polyatomic gas is inversely proportional to absolute temperature.
A. True
B. False

Answer: Option A

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