Exercise: Materials And Components

Questions for: Materials And Components

Assertion (A): Power loss in a conductor of resistance P = I2R.

Reason (R): When a conductor is carrying current with current density J as a result of applied field E, then heat developed/m3/ second = JE.

A:
Both A and R are true and R is correct explanation of A
B:
Both A and R are true but R is not correct explanation of A
C:
A is true but R is false
D:
A is false but R is true
Answer: A

Heat developed depends an power loss.

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Ferroelectric materials are those which
A:
cannot be polarized
B:
have a permanent polarization
C:
have ae equal to zero
D:
have μp = 0
Answer: B

Ferroelectric materials have permanent polarization.

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At room temperature, the current in intrinsic semiconductor is due to
A:
holes
B:
electrons
C:
ions
D:
holes and electrons
Answer: D

Both electrons and holes contribute to flow of current in semiconductors.

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Assertion (A): At a temperature of 1000 K, thermionic emission current is about 0.1 A/cm2 of surface.

Reason (R): Thermionic emission current is given by Ith = SA0 T2 e-Ew/kT.

A:
Both A and R are true and R is correct explanation of A
B:
Both A and R are true but R is not correct explanation of A
C:
A is true but R is false
D:
A is false but R is true
Answer: A

If different values are substituted in the equation for Ith the value of emission current comes out to be about 0.1 A/cm2.

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If ∈r' and ∈r" are the real and imaginary parts of complex dielectric constant ∈r, and δ is the loss angle. Then
A:
B:
C:
tan δ = ∈'∈"
D:
tan δ = 1 - ∈'
Answer: B

If ∈r" = 0, δ = 0.

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