Materials and Components Questions

• The induced magnetic dipole moment has a direction opposite to the applied magnetic field.
• A sample of N type semiconductor has an electron density of 6.25 x 1018/cm3 at 300 K. If intrinsic concentration of carriers in this sample is 2.5 x 1013/cm3 at this temperature, the hole density is
• When an electron moves at velocity v in combined electric and magnetic fields E and H, the Lorentz force F is F = - e(E + v x B).
• Iron has a body centred cubic structure.
• Sulphur hexafluoride is used in
• A rare gas has N atoms per m3. If electronic polarizability of single atom of this gas is ae, then
• M = (μr - 1)H.
• A parallel plate capacitor has area of plate equal to 1 m and distance between plates is also 1 m2. The lossy dielectric has a complex dielectric constant ∈r = ∈'r - j ∈"r. If the capacitor is represented by R and C is parallel, then
• Which of the following is used in temperature alarm circuits?
• The v-i characteristic shown in the given figure is for
• The Ohm's law for conduction in metals is
• Soft iron is suitable for making temporary magnets.
• A specimen of metal has n valence electrons per m3. If vx is the average velocity of these electrons, each having a charge e, the current density J is
• A metal has a large number of free electrons. If e is electronic charge and m is mass of electron and an electric field E is applied along (say) x direction, the electrons acquire a velocity having a component vx is x direction. Then
• If the operating temperature increases by 10°C, the rate of deterioration of solid dielectric becomes
• The measurement of Hall coefficient of a semiconductor with one type of charge carriers gives the information about
• When two conductors carry currents in the same direction the force is repulsive.
• When a trivalent impurity is added, the semiconductor becomes
• For dielectrics in alternating field, polarizability ae is a complex quantity. The imaginary part of ae is zero for
• Bitter powder patterns prove the existence of domains.