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Electronics and Communication Engineering - Materials and Components

Exercise : Materials and Components - Section 4
21.
Semiconductors have a positive temperature coefficient of resistivity.
True
False
Answer: Option
Explanation:

In semiconductors the temperature coefficient of resistivity is negative.

22.
From a homogeneous and isotropic dielectric material of dielectric constant ∈r, a small volume element is taken out creating a cavity. The field can be kept homogeneous if Di. (i.e., electric flux density inside the cavity) and D0 (i.e., electric flux density outside the cavity) are such that
D0 = Di
either (a) or (b)
Answer: Option
Explanation:

Since the field is homogeneous .

23.
An electrolytic capacitor can be used for
ac only
dc only
both ac and dc
high frequency ac
Answer: Option
Explanation:
No answer description is available. Let's discuss.
24.
Figure shows a composite capacitor. If CA, CB, CC are the capacitances of capacitors A, B, C, the overall capacitance C is
C = CA + CB + CC
C = (CA + CB) CC
C =
C =
Answer: Option
Explanation:

B and C are in series and A is in parallel with this combination.

25.
As regards ferromagnetic Curie temperature Qf and paramagnetic curie temperature θ
Qf > θ
θ > Qf
θ equal to or less than Qf
θ may be equal to less than or more Qf
Answer: Option
Explanation:
No answer description is available. Let's discuss.
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