Q. 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

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Q. 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

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Q. If m is the mass of electron cloud, the equation of motion of electron cloud in the presence of an alternating electric field is of the form

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Q. If Bmax is the maximum flux density, hysteresis loss is proportional to

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Q. If Bmax is the maximum flux density, eddy current loss is proportional to

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Q. A vacuum parallel plate capacitor is charged. The field between the plates is 2 x 10⁴ V/m. If the space between the plates is filled with a material having ∈ᵣ = 10, then the value of field in the dielectric will be

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Q. In p type semiconductor, the conductivity due to holes is (e = charge on hole, μp = hole mobility, p = hole concentration)

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Q. An electron is moving around a proton, in a circle of radius R. If flux density in the region is increased from zero to B, the force on the electron is

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Q. If μp is permanent dipole moment and T is absolute temperature, the orientation polarization of polyatomic gases is

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Q. Assertion (A): At a temperature of 1000 K, thermionic emission current is about 0.1 A/cm² of surface.Reason (R): Thermionic emission current is given by Ith = SA₀ T² e^(-Ew/kT).

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Q. At room temperature, the current in intrinsic semiconductor is due to

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Q. Ferroelectric materials are those which

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Q. 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.

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Q. Assertion (A): For Diamond, μᵣ = 1
Reason (R): Diamond is a diamagnetic material.

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Q. For a paramagnetic material, susceptiblity increases with increasing temperature.

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Q. Hydrogen is used in

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Q. Assertion (A): Ferroelectric materials have spontaneous polarization.
Reason (R): Above curie temperature, ∈ = C/(T-ϴ) for ferro-electric materials.

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Q. If e is the charge of an electron, R is the radius of its orbit and ω is the angular velocity of electron, the magnetic dipole moment μm of the orbit is |μm| = eωR².

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Q. If a piece of wood is placed in a magnetic field

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Q. The number of valence electrons in donor impurity are

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