Materials and Components Questions

• Antiferromagnetic materials do not have permanent dipoles.
• Silicon and germanium are elements in the
• An atom of polarizability a is placed in a homogeneous electric field E. The energy stored in polarized atom is
• A capacitor can be represented by a capacitance and resistance in parallel. For a good capacitor, this parallel resistance should be
• When a potential is applied across an intrinsic semiconductor, holes flow
• ∈0 has no other physical meaning than that of a fundamental conversion factor.
• n type semiconductors
• Assertion (A): Acceptor extrinsic semiconductor has higher conductivity than intrinsic semiconductor. Reason (R): Addition of p-type impurity produces an allowable discrete energy level just above valence band.
• In the wave mechanical theory, the maximum of the charge distribution in the ground state occurs for a distance from the nucleus equal to
• The colour code on a carbon resistor is brown-black-red-gold. The value of resistance is
• Tesla is a unit of
• The number of protons in germanium atom is
• A magnet does not attract
• At 0 K, silicon and germanium behave like monoatomic crystals.
• Two coaxial metallic cylinders have radii R1 and R2. The space between them is filled with a dielectric having dielectric constant ∈r. The capacitance per metre length is
• Hysteresis curve is associated with motion of domain walls.
• 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.