Exercise: Materials And Components

Questions for: Materials And Components

The phenomenon of dielectric hysteresis occurs with
A:
dc
B:
ac
C:
both ac and dc
D:
none of the above
Answer: B

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

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If Ī¼p is permanent dipole moment and T is absolute temperature, the orientation polarization of polyatomic gases is
A:
proportional to Ī¼p2T
B:
proportional to
C:
proportional to Ī¼p T
D:
proportional to
Answer: B

Orientation polarization = NĪ¼p2E/3 kT.

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Electrical contact materials used in switches, brushes, relay must possess
A:
high thermal conductivity and high melting point
B:
low thermal conductivity and low melting point
C:
high thermal conductivity and low melting point
D:
low thermal conductivity and high melting point
Answer: A

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

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The elements which become superconducting at extremely low temperatures are
A:
good conductors at room temperature
B:
ferromagnetic at room temperature
C:
relatively poor conductors at room temperature
D:
insulators at room temperature
Answer: C
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We can know the arrangement of atom in a material by studying electron diffraction pattern.
A:
True
B:
False
C:
D:
Answer: A
No answer description is available. Let's discuss.
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