Q. Dielectric constant of transformer oil is about

View solution

Q. 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.

View solution

Q. When a material becomes a superconductor, its resistivity becomes

View solution

Q. In a piezoelectric crystal, the application of mechanical force will cause

View solution

Q. Consider the following statement:

If an electric field is applied to an n type semiconductor bar, the electrons and holes move in opposite directions due to their opposite charges. The net currents is
1. both due to electrons and holes with electrons as majority carriers
2. sum of hole and electron currents
3. difference between electron and hole currents.

Which of above statements are correct?

View solution

Q. As the temperature of a pure silicon specimen is increased

View solution

Q. Assertion (A): In many materials, dielectric polarization causes mechanical distortion.
Reason (R): If dielectric polarization causes mechanical distortion then mechanical distortion must cause dielectric polarization.

View solution

Q. Semi conducting materials are all

View solution

Q. Silicon and germanium atoms combine orderly into array of atoms located in repetitive geometric pattern. This pattern is called

View solution

Q. In a pure sample of silicon

View solution

Q. Orbital magnetic dipole moment is due to the motion of electron in its orbit around nucleus.

View solution

Q. Assertion (A): ∈ᵣ can be determined experimentally by measuring the capacitance of a parallel plate capacitor with and without the dielectric.
Reason (R): Capacitance of a parallel plate capacitor = Ɛ₀ƐᵣA/d .

View solution

Q. Assertion (A): An electron having charge - e and mass m and lying in an electric field E is subjected to an acceleration - (e/m) E.

Reason (R): If there are n electrons/m³ moving with velocity vᵪ and each electron has a charge - e, the current density J = - n evᵪ.

View solution

Q. When a pentavalent impurity is added, the semiconductor becomes

View solution

Q. In body centred cubic structure, comers and centre of the cube are occupied by identical atoms.

View solution

Q. For a multiplate capacitor having n plates, A as area of each plate, the capacitance is proportional to

View solution

Q. The orientation polarization is

1. directly proportional to temperature
2. inversely proportional to temperature
3. inversely proportional to square of permanent dipole moment
4. directly proportional to square of permanent dipole moment.

Which of the above are correct?

View solution

Q. The relaxation time of electrons in a metal is of the order of

View solution

Q. Assertion (A): For elemental dielectrics, P = NaeEi where N is number of atoms/m³, P is polarization, ae is electronic polarization and Ei is internal electric field.

Reason (R): In elemental dielectrics there are no permanent dipoles or ions.

View solution

Q. The circumference of an electron orbit is equal to integer times the wavelength of electron.

View solution