Materials and components

1

As regards `in` 0 and `in` r (absolute and relative permittivity)

A. both ∈0 and ∈r can be interpreted in terms of atomic properties of medium
B. only ∈r can be interpreted in terms of atomic properties of medium
C. only ∈0 can be interpreted in terms of atomic properties
D. ∈r has no physical significance

2

Assertion (A): In a perfect capacitor, the current density is given by `omega` `in` 0E0`in` 'rcos(`omega`t + `90^circ`), where `in` 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

3

If e is the charge of an electron, R is the radius of its orbit and `omega` is the angular velocity of electron, the magnetic dipole moment `mu_`m of the orbit is |`mu_`m| = e`omega`R2.

A. True
B. False

4

Assertion (A): In imperfect capacitors, the current does not lead the applied ac voltage by `90^circ` .

Reason (R): When subjected to ac fields, the dielectric constant can be expressed as `in` 'r - j`in` "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

5

The core of a solenoid is made of material of relative permeability `mu_`r. A small cavity area dA and length dl is cut in the core. If it is desired that flux density in the cavity should be equal to B0

A. the fields inside and outside the cavity must be equal
B. the field inside the cavity must be made stronger than field outside the cavity
C. the field inside the cavity must be made weaker than the field outside the cavity
D. none of the above