# Electronics and Communication Engineering - Materials and Components

### Exercise :: Materials and Components - Section 1

41.

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

 A. True B. False

Explanation:

Angular quantum number determines the angular momentum of electron.

42.

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

Explanation:

If dielectric losses are zero, the current in capacitor leads the applied voltage by 90°.

Also imaginary part of is ∈r is zero.

43.

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

Explanation:

Increase of B with I is not linear. Hence R is false.

44.

Assertion (A): From the slope of the line in Figure, we can find permanent dipole moment of the molecules.

Reason (R): Total polarization of a polyatomic gas is given by P = N(ae + ai + μ2p / 3kT)E.

 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

Explanation:

The slope of the line in figure is .

Since the total polarization is as given by the expression, we can find the permanent dipole moment of the molecules from the slope.

45.

Assertion (A): If E is available energy state eV and EF is Fermi level, then probability of energy state E being occupied = 0.5.

Reason (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