Explore topic-wise MCQs in Testing Subject.

This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.

1.

Assertion (A): For a solenoid having N turns, .Reason (R): For all magnetic materials, B increases linearly with I.

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
2.

The unit for mmf is

A. A
B. Wb
C. T
D. V
Answer» B. Wb
Discussion
3.

In a homogeneous magnetic field H of a solenoid, the core carries a magnetic dipole moment M per unit volume equal to

A. μ0 H
B. μr H
C. (μr - 1) H
D. μoμr H
Answer» D. ŒºoŒºr H
Discussion
4.

A dielectric of relative permittivity ‚ààr is subjected to a homogeneous electric field E. The dipole moment P per unit volume is given by

A. P = constant
B. P = ‚àà0 E
C. P = ‚àà0(‚ààr - 1) E
D. P = ‚ààr E
Answer» D. P = ‚ààr E
Discussion
5.

If t is relaxation time and tc is average time between collisions, then in an isotropic metal

A. t = tc
B. t < tc
C. tc < t
D. T = 0.01 te
Answer» B. t < tc
Discussion
6.

The maximum temperature limit of class B insulation is

A. 90°C
B. 105°C
C. 120°C
D. 130°C
Answer» E.
Discussion
7.

Resistivity of rubber is about

A. 102 Ω-m
B. 10-2 Ω-m
C. 5 x 108 Ω m
D. 5 x 1012 Ω-m
Answer» E.
Discussion
8.

In carbon resistor colour code, the third band is red. It indicates

A. two zeros
B. three zeros
C. multiplier is 0.01
D. multiplier is 0.1
Answer» B. three zeros
Discussion
9.

For magnetic shielding, we need a ferromagnetic material.

A. 1
B.
C. Both A and R are true and R is correct explanation of A
D. Both A and R are true but R is not correct explanation of A
Answer» B.
Discussion
10.

In intrinsic semiconductors, the number of free electrons is equal to the number of mobile holes.

A. 1
B.
Answer» B.
Discussion
11.

Tesla is a unit of

A. flux
B. field strength
C. flux density
D. MMF
Answer» D. MMF
Discussion
12.

When an electric field E is applied to solid and liquid insulating materials, the internal field Ei acting at the location of atom is such that

A. Ei = E
B. Ei > E
C. Ei < E
D. Ei may be equal to or less than E
Answer» C. Ei < E
Discussion
13.

Assertion (A): Electron concentration n, hole concentration p and charge concentration ni are related by ni2 = np.Reason (R): p type semiconductor is obtained by adding trivalent impurity to intrinsic semiconductor.

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
14.

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

A. C,
B. , Q
C. ,
D. C, K
Answer» C. ,
Discussion
15.

The chemical properties of atoms are determined by all the electrons and their configuration.

A. 1
B.
Answer» C.
Discussion
16.

Assertion (A): Silicon is less sensitive to changes in temperature than germanium.Reason (R): Cut in voltage in silicon is less than that in germanium.

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
17.

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
18.

The quantum numbers associated with electron motion are designed as

A. a, b, c
B. h, k, l
C. n, m, l
D. h, n, l
Answer» D. h, n, l
Discussion
19.

M = (μr - 1)H.

A. 1
B.
C. second column of periodic table
D. third column of periodic table
Answer» B.
Discussion
20.

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
21.

Some typical examples of macroscopic quantities are

A. conductivity
B. µr
C. dielectric constant
D. all of the above
Answer» E.
Discussion
22.

For a given value (n) of principle quantum number, the number of possible electronic states are

A. n
B. n2
C. n3
D. n
Answer» C. n3
Discussion
23.

Assertion (A): Relaxation time and mean time between collisions are equal when scattering is isotropic.Reason (R): Mean free path of an electron λ, velocity of electron v and mean time between collisions tc are related as λ = vTc.

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
24.

A vacuum parallel plate capacitor is charged. The field between the plates is 2 x 104 V/m. If the space between the plates is filled with a material having ‚ààr = 10, then the value of field in the dielectric will be

A. 2 x 103 V/m
B. x 104 V/m
C. 210 x 104 V/m
D. 2 x 105 V/m
Answer» B. x 104 V/m
Discussion
25.

Assertion (A): Helium, Argon and Neon are gaseous at room temperature.Reason (R): The atoms in Helium, Argon and Neon are chemically extremely inactive.

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
26.

The minority carrier life time and diffusion constant in a semiconducting material are 100 μs and 100 cm2/s respectively. The diffusion length of carriers is

A. 0.1 cm
B. 0.01 cm
C. 0.0141 cm
D. 1 cm
Answer» B. 0.01 cm
Discussion
27.

If n denotes principal quantum number, the angular quantum number l = 0, 1... (n - 1).

A. 1
B.
C. Both A and R are true and R is correct explanation of A
D. Both A and R are true but R is not correct explanation of A
Answer» B.
Discussion
28.

At a very low temperature, a semiconductor

A. becomes a conductor
B. becomes an insulator
C. may become a conductor or an insulator
D. will remain a semiconductor becomes a conductor or an insulator
Answer» C. may become a conductor or an insulator
Discussion
29.

Assertion (A): Atomic number of sodium is 11.Reason (R): Sodium has a body centred cubic 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
30.

A parallel plate capacitor has its length, width and separation doubled. It fringing effects are neglected, to keep the capacitance same, the dielectric constant must be

A. halved
B. kept the same
C. doubled
D. made 4 times
Answer» B. kept the same
Discussion
31.

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
32.

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» B. Both A and R are true but R is not correct explanation of A
Discussion
33.

In paramagnetic materials

A. permanent magnetic dipoles exist but the interaction between neighbouring dipoles is negligible
B. permanent magnetic dipole do not exist
C. permanent magnetic dipoles exist and the interaction between neighbouring dipoles is very strong
D. permanent magnetic dipole moment may or may not exist
Answer» B. permanent magnetic dipole do not exist
Discussion
34.

Above ferroelectric curie temperature, spontaneous polarization in ferroelectric materials becomes stronger.

A. 1
B.
Answer» C.
Discussion
35.

If a piece of wood is placed in a magnetic field

A. the magnetic field will not be affected
B. the magnetic lines of force will bend towards the piece
C. the magnetic lines of force will bend away from the piece
D. the flux may increase or decrease
Answer» B. the magnetic lines of force will bend towards the piece
Discussion
36.

The dielectric losses do not depend on frequency.

A. 1
B.
C. Both A and R are true and R is correct explanation of A
D. Both A and R are true but R is not correct explanation of A
Answer» C. Both A and R are true and R is correct explanation of A
Discussion
37.

In crystalline solids, atoms are stacked in a regular manner.

A. 1
B.
C. Weiss temperature
D. Curie temperature
Answer» B.
Discussion
38.

For a paramagnetic material, susceptiblity increases with increasing temperature.

A. 1
B.
C. large size transformers
D. MCB
Answer» C. large size transformers
Discussion
39.

The temperature at which some materials become superconductors is called

A. Transition temperature
B. Curie temperature
C. Neel temperature
D. Onnes temperature
Answer» B. Curie temperature
Discussion
40.

Assertion (A): Diamond and carborudum are both very hard materials.Reason (R): Valence band can be extremely strong.

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
41.

The conductivity of intrinsic semiconductor is given by

A. eni(μp - μn)
B. eni(μp + μn)
C. ni(μp + μn)
D. ni(μpμn)
Answer» C. ni(Œºp + Œºn)
Discussion
42.

The attraction between the nucleus and valence electron of copper atom is

A. zero
B. weak
C. strong
D. either zero or strong
Answer» C. strong
Discussion
43.

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. 1
B.
Answer» B.
Discussion
44.

The number of protons in a silicon atom are

A. 4
B. 8
C. 12
D. 14
Answer» E.
Discussion
45.

Which element exhibits the property of inertia?

A. Resistance
B. Capacitance
C. Inductance
D. Both resistance and inductance
Answer» D. Both resistance and inductance
Discussion