Q. A single layer air cored coil has n turns and inductance L. If a new coil is formed by having 2n turns while keeping the coil length and diameter the same, the new inductance is

View solution

Q. The colour code on a carbon resistor is yellow-violet-orange. The value of resistance is

View solution

Q. A leaky dielectric has ∈ᵣ = ∈ᵣ' - j∈ᵣ". If a field E is applied, the current component in phase with E is proportional to ∈ᵣ".

View solution

Q. Assertion (A): In ionic dielectrics, P = Pe + Pi.

Reason (R): In ionic crystals, permanent electric dipole moment is zero.

View solution

Q. The current flow in a semiconductor is due to

View solution

Q. Assertion (A): Relative permittivity is determined by the atomic structure of the material.

Reason (R): Absolute permittivity is determined by the atomic structure of the material.

View solution

Q. Eddy current loss is

View solution

Q. Some ceramic materials become superconducting

View solution

Q. Assertion (A): Doping level in extrinsic semiconductors is very small.

Reason (R): Additional of impurity in the ratio of 1 part in 108 parts increases the number of charge carriers by about 20.

View solution

Q. The core of an atom consists of

View solution

Q. Assertion (A): Copper is a good conductor of electricity.

Reason (R): Copper has a face centred cubic lattice.

View solution

Q. When a dielectric is subjected to an electric field E, each volume element of dielectric can be considered to be carrying an electric dipole moment.

View solution

Q. A dielectric of relative permittivity ∈ᵣ is subjected to a homogeneous electric field E. The dipole moment P per unit volume is given by

View solution

Q. Which of these has the highest dielectric strength?

View solution

Q. For an insulating material, dielectric strength and dielectric losses should be

View solution

Q. Consider the following statements

1. An iron cored choke is non linear and passive device.
2. A carbon resistor kept in sunlight is a time invariant and passive device.
3. A dry cell is a time varying and active device.
4. An air capacitor is time invariant and passive device.

Of these statements

View solution

Q. The direction of force an a conductor carrying current and lying in a magnetic field can be found by using

View solution

Q. Assertion (A): Rochelle salt and Barium titanate are both ferroelectric.

Reason (R): Ferroelectric materials exhibit hysteresis effect.

View solution

Q. The units for electric dipole moment are

View solution

Q. The temperature coefficient of resistivity of semiconductors is

View solution