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Materials and Components MCQ Questions & Answers

Materials and Components MCQs : This section focuses on the "Materials and Components". These Multiple Choice Questions (MCQs) should be practiced to improve the Materials and Components skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.




Question 1

The conductivity of intrinsic semiconductor is given by

A. eni(μp - μn)
B. eni(μp + μn)
C. ni(μp + μn)
D. ni(μpμn)

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Question 2

Hydrogen is used in

A. large size transformers
B. MCB
C. large size generators
D. circuit breakers

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Question 3

In metals the valence electron wave functions are strongly perturbed by the presence of neighbouring atoms.

A. TRUE
B. FALSE

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Question 4

The number of valence electrons in donor impurity are

A. 5
B. 4
C. 3
D. 1

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Question 5

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

A. TRUE
B. FALSE

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Question 6

Assertion (A): For Diamond, μr = 1Reason (R): Diamond is a diamagnetic 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

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Question 7

At room temperature, the current in intrinsic semiconductor is due to

A. holes
B. electrons
C. ions
D. holes and electrons

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Question 8

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

A. zero
B. weak
C. strong
D. either zero or strong

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Question 9

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

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Question 10

The number of valence electrons in pentavalent impurity is

A. 5
B. 4
C. 3
D. 1

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Question 11

Material which lack permanent magnetic dipoles are known as

A. paramagnetic
B. diamagnetic
C. ferromagnetic
D. ferrimagnetic

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Question 12

For a permanent magnetic material

A. the residual induction and coercive field should be large
B. the residual induction and coercive field should be small
C. area of hysteresis loop should be small
D. initial relative permeability should be high

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Question 13

Diamond is a paramagnetic material.

A. TRUE
B. FALSE

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Question 14

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

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Question 15

The hysteresis phenomenon in ferromagnetic materials exists at all temperatures.

A. TRUE
B. FALSE

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Question 16

If the temperature of an extrinsic semiconductor is increased so that the intrinsic carrier concentration is doubled, then

A. the majority carrier density is doubled
B. the minority carrier density is doubled
C. the minority carrier density becomes 4 times the original value
D. both the majority and minority carrier densities double

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Question 17

For a paramagnetic material, susceptiblity increases with increasing temperature.

A. TRUE
B. FALSE

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Question 18

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

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Question 19

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

A. TRUE
B. FALSE

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Question 20

In a coaxial cable, braided copper is used for

A. conductor
B. shield
C. dielectric
D. jacket

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Question 21

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

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Question 22

Assertion (A): The conductivity of p type semiconductor is higher than that of intrinsic semiconductor.Reason (R): The addition of donor impurity creates additional energy levels below conduction band.

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

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Question 23

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

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Question 24

In atomic physics, a state with l = 0 is called p state.

A. TRUE
B. FALSE

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Question 25

Assertion (A): In imperfect capacitors, the current does not lead the applied ac voltage by 90°.Reason (R): When subjected to ac fields, the dielectric constant can be expressed as ∈'r - j∈"r.

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

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Question 26

Which element exhibits the property of inertia?

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

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Question 27

If e is the charge of an electron, R is the radius of its orbit and ω is the angular velocity of electron, the magnetic dipole moment μm of the orbit is |μm| = eωR2.

A. TRUE
B. FALSE

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Question 28

In a true valence crystal, the bonding between the atoms is accomplished by the sharing of valence electrons.

A. TRUE
B. FALSE

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Question 29

If a sample of germanium and a sample of silicon have the same impurity density and are kept at room temperature

A. both will have equal value of resistivity
B. both will have equal negative resistivity
C. resistivity of germanium will be higher than that of silicon
D. resistivity of silicon will be higher than that of germanium

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Question 30

The core of a coil has a length of 10 cm. The self inductance is 8 mH. If the core length is doubled, all other quantities remaining the same, the self inductance will be

A. 32 mH
B. 16 mH
C. 8 mH
D. 4 mH

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Question 31

The law J = σE, where J is current density, σ is electrical conductivity and E is field strength is

A. Ohm's law
B. Gauss law
C. Ampere's law
D. Biot-Savart law

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Question 32

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

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Question 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

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Question 34

Assertion (A): Magnetic susceptibility of diamagnetic materials is much less than that of paramagnetic materials.Reason (R): For diamagnetic as well as paramagnetic materials, μr is nearly equal to 1.

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

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Question 35

There is no hysteresis phenomenon is any dielectric material.

A. TRUE
B. FALSE

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Question 36

Assertion (A): Power loss in a conductor of resistance P = I2R.Reason (R): When a conductor is carrying current with current density J as a result of applied field E, then heat developed/m3/ second = JE.

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

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Question 37

If the diameter of a wire is doubled, its current carrying capacity becomes

A. one-fourth
B. half
C. twice
D. four times

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Question 38

Which capacitor-store higher amount of energy?

A. Air capacitor
B. Paper capacitor
C. Mica capacitor
D. Plastic film capacitor

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Question 39

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

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Question 40

Assertion (A): In a perfect capacitor, the current density is given by ω ∈0E0∈'rcos(ωt + 90°), where ∈r' is real part of dielectric constant.Reason (R): In a perfect capacitor, dielectric losses are zero.

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

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Question 41

The units of μ0 and μr are

A. H/m for both
B. H/m for μr and no units for μ0
C. H/m for μ0 and no units for μr
D. Wb/m for μ0 and no units for μr

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Question 42

Assertion (A): Electronic and Ionic polarization in a polyatomic gas are independent of temperature.Reason (R): The orientation polarization is independent of temperature.

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

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Question 43

Ferroelectric materials are those which

A. cannot be polarized
B. have a permanent polarization
C. have ae equal to zero
D. have μp = 0

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Question 44

Two materials having temperature coefficients of 0.004 and 0.0004 respectively are joined in series. The overall temperature coefficient is likely to be

A. 0.08
B. 0.04
C. 0.001
D. 0.0001

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Question 45

Which of the following are donor impurities? GoldPhosphorusBoronAntimonyArsenicInduim Select the correct answer using the following codes

A. 1, 2, 3
B. 1, 2, 4, 6
C. 3, 4, 5, 6
D. 2, 4, 5

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