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Materials and Components – Section 2(Page 4)

1 Comment / Electronics and Communications

Materials and Components – Section 2

31. The relationship of hysteresis loss to maximum flux density was first determined by
A. C. Steinmetz
B. G.R. Kirchoff
C. Mr. Laplace
D. Mr. Ampere

Answer: Option A
32.  In metals the thermal conductivity K and electrical conductivity σ are related as (K/σT) = L, L is known as
A. Lattice constant
B. Lorentz number
C. Lanevin function
D. Larmor number

Answer: Option B

 

33. Assertion (A): If WF is Fermi energy, v is velocity of electron and m is mass of electron, then
.

Reason (R): Conductivity of a metal depends on temperature and impurity concentration.
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: Option B
34.  Dielectric constant of transformer oil is about
A. 1
B. 4
C. 10
D. 20

Answer: Option B

 

35.  Assertion (A): When an electron is revolving in its orbit and magnetic field is also present, the angular frequency of electron will be affected by the magnetic field.

Reason (R): In the case of electron revolving in its orbit in the presence of magnetic field, the orbital magnetic dipole moment is not affected by the presence of magnetic field.
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: Option C

Explanation:

Orbital magnetic moment is equal to (-e/2m).

 

36.  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: Option A
37.  Rochelle salt is a ferroelectric material.
A. True
B. False

Answer: Option A
38.  Paramagnetic materials have permanent magnetic dipoles but interaction between neighbouring dipoles is negligible.
A. True
B. False

Answer: Option A
39. Assertion (A): If difference between static and optical dielectric constant is high, the mechanical compressiblity of that material is also high.

Reason (R): For soft ions, ionic polarization per unit field is higher than that of hard 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: Option A
40.  Assertion (A): In Figure, the intercept of the line on y-axis is equal to N (ae + ai), where N is number of atoms/m3, ae is electronic polarizability and ai is ionic polarizability.

Reason (R): ae and ai are 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

Answer: Option A

Explanation:

The intercept on y-axis equals N (ae + ai).

This intercept is constant because ae and ai are independent of temperature.

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