The law that (where K is thermal conductivity, ? is electrical conductivity and

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Question
The law that (where K is thermal conductivity, ? is electrical conductivity and T is absolute temperature) for all metals is equal to a universal constant is known as
Options
A. Lorentz law
B. Wiedemann Franz law
C. Curie Weiss law
D. Kittel law

Correct Answer

Lorentz law

Materials and Components problems

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2. In a ferromagnetic material, the internal field seen by a dipole is
Options
A. equal to applied field
B. equal to applied field minus a contribution from neighbouring dipoles
C. equal to applied field plus a contribution from neighbouring dipoles
D. equal to or less than applied field

4. In its lowest state, the electron is bound to the field of proton by an energy equal to
Options
A. 100.5 eV
B. 51.2 eV
C. 13.6 eV
D. 0.2 eV

6. The chemical properties of atoms are determined by all the electrons and their configuration.
Options
A. True
B. False

8. From a homogeneous and isotropic dielectric material of dielectric constant ?_r, a small volume element is taken out creating a cavity. The field can be kept homogeneous if D_i. (i.e., electric flux density inside the cavity) and D₀ (i.e., electric flux density outside the cavity) are such that
Options
A. D₀ = D_i
B.
C.
D. either (a) or (b)

9. At T = 0, the resistivity of a perfect single crystal of a metal is
Options
A. 0
B. low
C. high
D. finite

10. The iron core of a coil is removed so that it becomes an air cored coil. Its inductance will
Options
A. increase
B. decrease
C. remain the same
D. may increase or decrease

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