This set of Manufacturing Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Electrical Properties Of Materials”.
1. Which of the following is the correct equation for De Broglie’s wavelength λ?
a) λ=h /mv
b) λ=h /m
c) λ=h /v
d) λ=mv/ h
View Answer
Explanation: De Broglie’s wavelength λ=h⁄mv. λ represents wavelength, h is Plancks constant, m represent mass and v represents velocity.
2. With an increase in the mean free path of a crystal, conductivity of a crystal.
a) Increases
b) Decreases
c) Remains constant
d) None of the mentioned
View Answer
Explanation: Conductivity increases with an increase in the mean free path of crystal. Conductivity is inversely proportional to resistance of a material.
3. Resistivity of silver in ohm-m has an order of :
a) 10-2
b) 10-3
c) 10-5
d) 10-9
View Answer
Explanation: Silver has lowest conductivity so resistivity is equal to 10-9 ohm-m.
4. Resistivity of iron in ohm-m has an order of :
a) 10-2
b) 10-6
c) 10-5
d) 10-9
View Answer
Explanation: Iron has medium conductivity so resistivity is equal to 10-6 ohm-m. Silver has lowest conductivity.
5. Resistivity of bismuth in ohm-m has an order of :
a) 10-4
b) 10-3
c) 10-5
d) 10-9
View Answer
Explanation: Bismuth has low conductivity so resistivity is equal to 10-4. Silver has lowest conductivity.
6. For insulators value of Energy gap in electron Volt i.e. eV ranges as :
a) Eg < 3
b) Eg < 1
c) Eg > 1
d) Eg > 3
View Answer
Explanation: For insulator Electric gap is very large and is generally greater than 3eV. It requires large energy to cross electron along the gap.
7. Which of the following equation may represent the property of metal, if Eg stands for energy gap in electron volt?
a) Eg < 3
b) Eg < 1
c) Eg > 1
d) Eg > 3
View Answer
Explanation: For conductors Electric gap is very small and is generally smaller than 1eV. For insulator Electric gap is very large and is generally greater than 3eV.
8. Resistance of a 200 meter long cooper wire is equal to 20 ohm. Its diameter is 0.44mm. Its specific resistance in ohm-m is equal to :
a) 1.520 * 10-8
b) 1.520 * 10-7
c) 1.520 * 10-6
d) 1.520 * 10-5
View Answer
Explanation: A = 3.14*d2/4 and resistivity = R*A/l, where ‘a’ is the area of cross section of wire and ρ is specific resistance.
9. Resistance of a 10 meter long cooper wire is equal to 2 ohm. Its diameter is 0.44mm. Its specific resistance in ohm-m is equal to :
a) 1.520 * 10-8
b) 3.041* 10-8
c) 1.520 * 10-6
d) 1.520 * 10-5
View Answer
Explanation: A = 3.14*d2/4 and resistivity = R*A/l, where ‘a’ is the area of cross section of wire and ρ is specific resistance.
10. With an increase in temperature of a semiconductor, resistance of semiconductor.
a) Increases
b) Decreases
c) Remains Constant
d) None of the mentioned
View Answer
Explanation: Semiconductor has a negative temperature coefficient of resistance. Their resistance increases with a decrease in temperature.
Sanfoundry Global Education & Learning Series – Manufacturing Engineering.
To practice all areas of Manufacturing Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.