Materials and Components Questions

• In metals the valence electron wave functions are strongly perturbed by the presence of neighbouring atoms.
• The core of a coil has a length of 10 cm. The self inductance is 8 mH. If the core length is doubled, all other quantities remaining the same, the self inductance will be
• Assertion (A): For a solenoid having N turns, . Reason (R): For all magnetic materials, B increases linearly with I.
• The law J = σE, where J is current density, σ is electrical conductivity and E is field strength is
• If ∈r' and ∈r" are the real and imaginary parts of complex dielectric constant ∈r, and δ is the loss angle. Then
• Diamond is a paramagnetic material.
• Assertion (A): Silicon is less sensitive to changes in temperature than germanium. Reason (R): Cut in voltage in silicon is less than that in germanium.
• The number of valence electrons in pentavalent impurity is
• There is no hysteresis phenomenon is any dielectric material.
• The hysteresis phenomenon in ferromagnetic materials exists at all temperatures.
• In paramagnetic materials
• The apparent capacitance at a high angular frequency ω of an air cored capacitor having capacitance C and inductance L is given by
• Ferroelectric materials are those which
• At room temperature, the current in intrinsic semiconductor is due to
• Assertion (A): Atomic number of sodium is 11. Reason (R): Sodium has a body centred cubic lattice.
• Which of the following are donor impurities? Gold Phosphorus Boron Antimony Arsenic Induim Select the correct answer using the following codes
• Assertion (A): Power loss in a conductor of resistance P = I2R. Reason (R): When a conductor is carrying current with current density J as a result of applied field E, then heat developed/m3/ second = JE.
• When an electric field E is applied to solid and liquid insulating materials, the internal field Ei acting at the location of atom is such that
• The number of valence electrons in donor impurity are
• Assertion (A): In imperfect capacitors, the current does not lead the applied ac voltage by 90°. Reason (R): When subjected to ac fields, the dielectric constant can be expressed as ∈'r - j∈"r.