Electrical conductivity of metals expressed in ohm-1 m-1 is of the order of 1010

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Question
Electrical conductivity of metals expressed in ohm^-1 m^-1 is of the order of
Options
A. 10¹⁰
B. 10⁵
C. 10^-4
D. 10^-6

Correct Answer

10⁵

Explanation

Conductivity is reciprocal of resistivity. Since resistivity of metals is around 10^-7 ohm-m, conductivity is about 10⁷ ohm^-1 m^-1. So 10⁵ is the nearest value.

Materials and Components problems

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2. In a metal the probability of a state 0.1 eV below Fermi level being occupied
Options
A. is more than the probability of state 0.1 eV above Fermi level being occupied
B. is the same as the probability of state 0.1 eV above Fermi level being occupied
C. is less than the probability of state 0.1 eV above Fermi level being occupied
D. may be equal to or more or less than the probability of state 0.1 eV above Fermi level being occupied

3. 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

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

5. 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)

6. In a polyatomic gas, the types of polarization which exist together are
Options
A. electronic and orientational
B. electronic and ionic
C. ionic and orientational
D. electronic, orientational and ionic

8. An electron in a homogeneous magnetic field and having velocity perpendicular to the direction of field moves
Options
A. perpendicular to the field
B. along the field
C. along a straight line inclined at 45� to field
D. in a circular path

9. An homogeneous dielectric material is subjected to an electric field E. If a small cavity is made inside the material, the electric field intensity inside and outside the cavity are different.
Options
A. True
B. False

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