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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Q. In a piezoelectric crystal, the application of mechanical force will cause

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Q. Consider the following statement:

If an electric field is applied to an n type semiconductor bar, the electrons and holes move in opposite directions due to their opposite charges. The net currents is
1. both due to electrons and holes with electrons as majority carriers
2. sum of hole and electron currents
3. difference between electron and hole currents.

Which of above statements are correct?

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Q. As the temperature of a pure silicon specimen is increased

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Q. Assertion (A): In many materials, dielectric polarization causes mechanical distortion.
Reason (R): If dielectric polarization causes mechanical distortion then mechanical distortion must cause dielectric polarization.

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