Questions and answers for exam Preparation

MCQs

Total Questions : 788 | Page 1 of 79 pages

Question 1.

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

both ∈0 and ∈r can be interpreted in terms of atomic properties of medium
only ∈r can be interpreted in terms of atomic properties of medium
only ∈0 can be interpreted in terms of atomic properties
∈r has no physical significance

Discuss Question

Answer: Option B. -> only ∈r can be interpreted in terms of atomic properties of medium

Question 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.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true but R is false
A is false but R is true

Discuss Question

Answer: Option A. -> Both A and R are true and R is correct explanation of A

Question 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.

True
False

Discuss Question

Answer: Option B. -> False

Question 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.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true but R is false
A is false but R is true

Discuss Question

Answer: Option A. -> Both A and R are true and R is correct explanation of A

Question 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

the fields inside and outside the cavity must be equal
the field inside the cavity must be made stronger than field outside the cavity
the field inside the cavity must be made weaker than the field outside the cavity
none of the above

Discuss Question

Answer: Option B. -> the field inside the cavity must be made stronger than field outside the cavity

Question 6. 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

32 mH
16 mH
8 mH
4 mH

Discuss Question

Answer: Option D. -> 4 mH
Answer: (d).4 mH

Question 7. Assertion (A): Electronic and Ionic polarization in a polyatomic gas are independent of temperature.
Reason (R): The orientation polarization is independent of temperature.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not correct explanation of A
A is true but R is false
A is false but R is true

Discuss Question

Answer: Option C. -> A is true but R is false
Answer: (c).A is true but R is false

Question 8. Two materials having temperature coefficients of 0.004 and 0.0004 respectively are joined in series. The overall temperature coefficient is likely to be

0.08
0.04
0.001
0.0001

Discuss Question

Answer: Option C. -> 0.001
Answer: (c).0.001

Question 9. Diamond is a paramagnetic material.

True
False
May be True or False
Can't say

Discuss Question

Answer: Option B. -> False
Answer: (b).False

Question 10. 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