Q. In crystalline solids, atoms are stacked in a regular manner.

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Q. The temperature below which certain materials are antiferromagnetic and above which they are paramagnetic is called

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Q. In metals, the average drift velocity of electron per unit field is called mobility.

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Q. Ferrites have

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Q. In intrinsic semiconductors, the number of free electrons is equal to the number of mobile holes.

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Q. Assertion (A): Relaxation time and mean time between collisions are equal when scattering is isotropic.

Reason (R): Mean free path of an electron λ, velocity of electron v and mean time between collisions tc are related as λ = vTc.

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Q. Assertion (A): Copper is a monoatomic solid.

Reason (R): In a metal the valence electrons belong to all atoms.

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Q. The heat developed per m³ per second (W) in a conductor having a conductivity σ and a field E is

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Q. The number of valence electrons in acceptor impurity are

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Q. If q is charge on an electron, R is radius of electron orbit and ω is angular velocity of electron rotation, the magnetic dipole moment of electron in orbit is

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Q. In a homogeneous magnetic field H of a solenoid, the core carries a magnetic dipole moment M per unit volume equal to

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Q. The field pattern of a solenoid is similar to that of bar magnet.

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Q. Assertion (A): Silicon is the most favoured semiconductor material.
Reason (R): PIV for silicon diode is more than that for germanium diode.

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Q. Assertion (A): When cathode temperature is increased from 2500 K to 2550 K, thermionic emission current may increase by about 50%.
Reason (R): Thermionic emission current ∝ T² e^(-Ew/kT).

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Q. The relationship of hysteresis loss to maximum flux density was first determined by

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Q. In metals the thermal conductivity K and electrical conductivity σ are related as (K/σT) = L, L is known as

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Q. Assertion (A): If WF is Fermi energy, v is velocity of electron and m is mass of electron, then 1/2mv² = WF .
Reason (R): Conductivity of a metal depends on temperature and impurity concentration.

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Q. Dielectric constant of transformer oil is about

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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.

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

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