Q. Assertion (A): Intrinsic resistivity of silicon is lower than that of germanium.

Reason (R): Magnitude of free electron concentration in germanium is more than that of silicon.

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Q. The units for ∈ᵣ are

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Q. The real part of complex dielectric constant and tanδ for a dielectric are 2.1 and 5 x 10¯⁴ at 100 Hz respectively. The imaginary part of dielectric constant at 100 Hz is

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Q. A copper atom is neutral. Its core has a net charge of

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Q. As the temperature of semiconductor is increased

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Q. In anti-ferromagnetic materials, the graph of susceptibility versus temperature shows a sharp maximum at a certain temperature. This temperature is known as

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Q. The wavelength of light emitted by GaAs laser is 8670 x 10¯¹ᴼ m. If h = 6.626 x 10¯³⁴ Js, velocity of light = 3 x 10⁸ m/s and eV = 1.602 x 10¯¹⁹ J, the energy gap in GaAs is

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Q. Diamagnetic materials do not have permanent magnetic dipoles.

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Q. A piece of copper and another piece of Germanium are cooled from 30°C to 80 K. The resistance of

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Q. The dipole moment per unit volume P as a function of E for an insulator is

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Q. A good dielectric should have

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Q. Magnetic hysteresis phenomenon is explained by

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Q. The relation between thermal conductivity K (W/m/°C), heat flow density Q (watt/m²) and dT/dx (°C per metre) is

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Q. Assertion (A): The equation D = ∈₀∈ᵣE is applicable only to isotropic materials.

Reason (R): In polycrystalline materials, the directional effects are absent.

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Q. Assertion (A): For a dielectric, P = ∈₀(∈ᵣ - 1) E.

Reason (R): Dipole moment per unit volume is called polarization of dielectric.

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Q. Assertion (A): Ferrites are very useful at very high frequencies.

Reason (R): Ferrites have high permeability and high resistivity.

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Q. In a conductor the current flow is due to

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Q. 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).

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Q. When Schrodinger equation is applied to the motion of electron in the field of protons, the physically acceptable solutions for the wave function exist for quantum number which are

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Q. For dielectrics in alternating field, polarizability αe is a complex quantity. The imaginary part of ae is zero for

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