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Electronics and Communication Engineering - Materials and Components

Exercise : Materials and Components - Section 3
26.
If a capacitor C having selectivity factor Q is scaled down in all its dimensions by a factor K without any altering the dielectric material, the new capacitor will have capacitance and selectivity as
C,
, Q
,
C, K
Answer: Option
Explanation:

Since the dimension of plates is scaled down by K, the area decreases by a factor of K2, the distance between plates decreases by a factor of K.

Therefore, capacitance changes to .

The selectivity will not be affected.

27.
The hysteresis loss is
proportional to frequency
independent of frequency
proportional to (frequency)2
proportional to
Answer: Option
Explanation:
No answer description is available. Let's discuss.
28.
If m, v, r are the mass, velocity and radius of orbit of electron and h is Planck's constant, quantum condition for electron's orbit is
Answer: Option
Explanation:

For stable circular orbit angular momentum is equal to integer times .

29.

Assertion (A): For a magnetic material M = (μr - 1) H, where M is magnetic dipole moment/m3, H is field intensity A/m and μr is relative permeability.

Reason (R): μr can have any value from 0 to hundreds of thousands.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true but R is false
A is false but R is true
Answer: Option
Explanation:

μr is always more than 1. It cannot be 0 or less than 1.

30.
As regards ∈0 and ∈r (absolute and relative permittivity)
both ∈0 and ∈r can be interpreted in terms of atomic properties of medium
only ∈r can be interpreted in terms of atomic properties of medium
only ∈0 can be interpreted in terms of atomic properties
∈r has no physical significance
Answer: Option
Explanation:
No answer description is available. Let's discuss.
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