Explore topic-wise MCQs in Materials and Components.

This section includes 29 Mcqs, each offering curated multiple-choice questions to sharpen your Materials and Components knowledge and support exam preparation. Choose a topic below to get started.

1.

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
A. 32
B. 16
C. 8
D. 4
Answer» D. 4
Discussion
2.

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.
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» D. A is false but R is true
Discussion
3.

Assertion (A): Resistivity of a perfect single crystal of a metal goes to zero as T approaches zero.

Reason (R): Scattering of electrons is due to deviations from perfect periodicity of lattice.
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» C. A is true but R is false
Discussion
4.

Assertion (A): Holes are majority carriers in p type semiconductor.

Reason (R): In p type semiconductor, the electrons produced by thermal agitation recombine with holes.
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» B. Both A and R are true but R is not correct explanation of A
Discussion
5.

When an electron moves at velocity v in combined electric and magnetic fields E and H, the Lorentz force F is F = - e(E + v x B).
A. True
B. False
Answer» B. False
Discussion
6.

Assertion (A): Relative permittivity is determined by the atomic structure of the material.

Reason (R): Absolute permittivity is determined by the atomic structure of the material.
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» D. A is false but R is true
Discussion
7.

Assertion (A): Rochelle salt and Barium titanate are both ferroelectric.

Reason (R): Ferroelectric materials exhibit hysteresis effect.
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» C. A is true but R is false
Discussion
8.

Assertion (A): Intrinsic resistivity of silicon is lower than that of germanium.

Reason (R): Magnitude of free electron concentration in germanium is more than that of silicon.
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» E.
Discussion
9.

The orientation polarization is

1.directly proportional to temperature

2.inversely proportional to temperature

3.inversely proportional to square of permanent dipole moment

4.directly proportional to square of permanent dipole moment.

Which of the above are correct?
A. 1 and 3 only
B. 2 and 3 only
C. 1 and 4 only
D. 2 and 4 only
Answer» E.
Discussion
10.

Assertion (A): An electron having charge - e and mass m and lying in an electric field E is subjected to an acceleration - (e/m) E.

Reason (R): If there are n electrons/m3 moving with velocity vx and each electron has a charge - e, the current density J = - n evx
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» C. A is true but R is false
Discussion
11.

If v is the velocity of electron, tc is the average time between collisions, the mean free path = vtc.
A. True
B. False
Answer» B. False
Discussion
12.

When a pentavalent impurity is added, the semiconductor becomes
A. p
B. B.
C. type
D. intrinsic
E. neutral
Answer» C. type
Discussion
13.

In a metal, the drift velocity of electrons in the presence of a electric field E is
A. proportional to E
B. proportional to -E
C. inversely proportional to E
D. proportional to E2
Answer» B. proportional to -E
Discussion
14.

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

Reason (R): r can have any value from 0 to hundreds of thousands.
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» D. A is false but R is true
Discussion
15.

The hysteresis loss is
A. proportional to frequency
B. independent of frequency
C. proportional to (frequency)2
D. proportional to
Answer» B. independent of frequency
Discussion
16.

Assertion (A): Orbital magnetic moment of an electron in an atom is of the order of 1 Bohr magneton.

Reason (R): 1 Bohr magneton = 9.27 x 10-24 A/m2.
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» C. A is true but R is false
Discussion
17.

As per Bohr's postulate, only those circular orbits are stable for which the angular momentum is equal to an integer times .
A. True
B. False
Answer» B. False
Discussion
18.

Assertion (A): For elemental dielectrics, P = NaeEi where N is number of atoms/m3, P is polarization, ae is electronic polarization and Ei is internal electric field.

Reason (R): In elemental dielectrics there are no permanent dipoles or ions.
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» B. Both A and R are true but R is not correct explanation of A
Discussion
19.

The relaxation time of electrons in a metal is of the order of
A. 10-6 secs
B. 10-10 secs
C. 10-14 secs
D. 10-20 secs
Answer» D. 10-20 secs
Discussion
20.

Assertion (A): Ferromagnetic materials possess ferromagnetic properties only when temperature is less than paramagnetic curie temperature.

Reason (R): For a ferromagnetic material for T > f.
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» B. Both A and R are true but R is not correct explanation of A
Discussion
21.

For a polyatomic gas, the equation relating dielectric constant r with molecular properties is
A.
B.
C. C.
D. D.
Answer» B.
Discussion
22.

The resistivity of intrinsic semiconductors, at room temperature, is of the order of
A. 1 -m
B. 1000 -m
C. 106 -m
D. 10-3 -m
Answer» B. 1000 -m
Discussion
23.

Assertion (A): For most metals, Fermi energy EF is less than 10 eV.

Reason (R): Fermi level of a metal is given by EF = 3.64 x 10-19 (n)2/3 where n is number of free electrons/m3 of metal.
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» B. Both A and R are true but R is not correct explanation of A
Discussion
24.

Assertion (A): The resistance of a copper specimen changes by about 22% when temperature is increased from room temperature to 700 C.

Reason (R): The physical properties of a material are determined mostly by the extent of impurities.
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» C. A is true but R is false
Discussion
25.

Assertion (A): Both sodium and ferrous are ferromagnetic.

Reason (R): Both sodium and ferrous have body centred cubic structure.
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» C. A is true but R is false
Discussion
26.

As regards dielectric constant r
A. the units are farads/m
B. the units are newton/coulomb
C. it is dimensionless
D. the units are farads
Answer» D. the units are farads
Discussion
27.

A single layer air cored coil has n turns and inductance L. If a new coil is formed by having 2n turns while keeping the coil length and diameter the same, the new inductance is
A. 0.5 L
B. L
C. 2 L
D. 4 L
Answer» E.
Discussion
28.

Consider the following statement: In case of a superconductor

1.B = 0

2. r is high

3.diamagnetism is high

4.transition temperature varies with isotopic mass.

Of the above statements
A. 1 and 2 are correct
B. 2, 3, 4 are correct
C. 1, 3, 4 are correct
D. 2, 4 are correct
Answer» D. 2, 4 are correct
Discussion
29.

Assertion (A): In liquids and glassy substances, dielectric losses occur.

Reason (R): The orientation polarization in many substances is frequency dependent.
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» B. Both A and R are true but R is not correct explanation of A
Discussion