Physics for Electrical Engineering: Unit II: a. Electrical Properties of Materials
Assignment Problems
Electrical Properties of Materials | Physics for Electrical Engineering
Physics for Electrical Engineering: Unit II: Electrical and Magnetic Properties of Materials : Assignment Problems
ASSIGNMENT PROBLEMS
1.
A copper wire whose diameter is 0.16 cm carries steady current of 10 A. What is
the current density of the wire? Also calculate the drift velocity of the
electrons in copper.
Given:
Density of electron in copper 8.5 × 1028 m - 3
[Ans: J = 497.6 × 104
A/m2, vd = 3.6 × 10-4 m/s]
2. The density and atomic weight of copper is
8900 kgm -3 and 63.5 respectively. The relaxation time of electrons
in copper at 300 K is 10- 14 seconds. Calculate the electrical conductivity
of copper. [Ans: 2.375 × 107 Ω-1m-1]
3.
The thermal and electrical conductivities of Cu at 20°C are 390 Wm -1K-1 and 5.87 ×
107 Ω-1m-1 respectively. Calculate the Lorentz number. [Ans: 2.267 × 10-8 WΩK-2]
4.
Using Fermi function, evaluate the temperature at which there is 1% probability
that an electron in a metal will have an energy 0.5 eV above EF of 5
eV. [Ans: 1260 K]
5.
Use the Fermi distribution function to obtain the value of F(E) for E-EF=0.01
eV at 300 K.[Ans: F(E)= 0.4045 ] [1 eV = 1.6 × 10-19 J 1J =1 / 1.6 x
10-19 eV]
Physics for Electrical Engineering: Unit II: a. Electrical Properties of Materials : Tag: : Electrical Properties of Materials | Physics for Electrical Engineering - Assignment Problems
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