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Electronics and Communication Engineering - Materials and Components

Exercise : Materials and Components - Section 7
11.

Assertion (A): The angular momentum of an atom is due to three contributions viz. orbital, electron spin and nuclear spin.

Reason (R): The nuclear spin magnetic moment is much more than electron spin magnetic moment.

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:

Nuclear spin is of the same order as electron sum.

12.
If WF is the Fermi level, then in a metal at T = 0
all energy levels above WF filled, all those below WF are empty
all energy levels below WF are filled, all those above WF are empty
some energy levels, both below and above WF, are filled
all energy levels below and above WF are filled
Answer: Option
Explanation:
No answer description is available. Let's discuss.
13.
Silicon and germanium have diamond structure. The number of atoms in a volume equal to a3 where a is the edge of elementary cube are
32
16
8
4
Answer: Option
Explanation:
No answer description is available. Let's discuss.
14.
If the radius of electron cloud around the nucleus of a rare gas atom is R, the electronic polarizability of the atom is porportional to
R
R2
R3
Answer: Option
Explanation:

Since (∈r - 1) = 4p NR3, electronic polarizability ∝ R3.

15.
By inserting a plate of dielectric between the plates of a parallel plate capacitor, the energy stored in the capacitor is increased five times. The dielectric constant of material is
5
25
Answer: Option
Explanation:

Capacitance is directly proportional to dielectric constant.

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