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Electronics and Communication Engineering - Materials and Components

Exercise : Materials and Components - Section 8
36.
The elements which become superconducting at extremely low temperatures are
good conductors at room temperature
ferromagnetic at room temperature
relatively poor conductors at room temperature
insulators at room temperature
Answer: Option
Explanation:
No answer description is available. Let's discuss.
37.
Electrical contact materials used in switches, brushes, relay must possess
high thermal conductivity and high melting point
low thermal conductivity and low melting point
high thermal conductivity and low melting point
low thermal conductivity and high melting point
Answer: Option
Explanation:

Heat generated at contact should be dissipated quickly and contact should not melt.

38.
If μp is permanent dipole moment and T is absolute temperature, the orientation polarization of polyatomic gases is
proportional to μp2T
proportional to
proportional to μp T
proportional to
Answer: Option
Explanation:

Orientation polarization = Nμp2E/3 kT.

39.
The phenomenon of dielectric hysteresis occurs with
dc
ac
both ac and dc
none of the above
Answer: Option
Explanation:

Hysteresis phenomenon occurs when direction of electric field is changed. This can happen only with ac.

40.
The induced magnetic dipole moment is independent of the permanent magnetic dipole moment.
True
False
Answer: Option
Explanation:
No answer description is available. Let's discuss.
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