Materials and Components Questions

• The resistivity of intrinsic semiconductors, at room temperature, is of the order of
• The electric dipole moment of a neutral system of point charges Q1, Q2.... is Qiri . The charges Qi
• If m, v, r are the mass, velocity and radius of orbit of electron and h is Planck's constant, quantum condition for electron's orbit is
• The capacitance of an insulated conducting sphere of radius R in vacuum is
• Thermistor is used in
• The hysteresis loss is
• Resistivity of rubber is about
• In terms of classical representation of electrons
• Some typical examples of macroscopic quantities are
• Assertion (A): For a magnetic material M = (μr - 1) H, where M is magnetic dipole moment/m3, H is field intensity A/m and μr is relative permeability. Reason (R): μr can have any value from 0 to hundreds of thousands.
• For small size high frequency coils, the most common core material is
• High frequency inductors and capacitors are commonly plated with silver. The main purpose of this is to
• Nichrome is used for
• Assertion (A): Metals are better heat conductors than insulators. Reason (R): If is temperature gradient, Q is heat flow density and K is thermal conductivity, then Q = - K (dT/dx).
• Semiconductors have a positive temperature coefficient of resistivity.
• An electrolytic capacitor can be used for
• For a given value (n) of principle quantum number, the number of possible electronic states are
• A sheet of bakelite is inserted between the plates of an air capacitor. The capacitance will
• In a virgin specimen of iron, the direction of spontaneous magnetisation varies from domain to domain.
• The orientation polarization of a polyatomic gas is inversely proportional to absolute temperature.