This set of Basic Electrical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Dielectric Strength”.
1. The unit for dielectric strength is ____________
a) V/m2
b) MV/m2
c) MV/m
d) Vm
View Answer
Explanation: Dielectric strength is the potential gradient required to cause a breakdown in the material. Potential gradient is the ratio of voltage and length, its unit is MV/m.
2. If the Voltage increases, what happens to dielectric strength?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
View Answer
Explanation: Dielectric strength is the potential gradient required to cause a breakdown in the material. Potential gradient is the ratio of voltage and length. Hence as potential increases, dielectric strength also increases.
3. If the potential difference in a material is 4MV and the thickness of the material is 2m, calculate the dielectric strength.
a) 2MV/m
b) 4MV/m
c) 6MV/m
d) 8MV/m
View Answer
Explanation: Dielectric strength is the potential gradient required to cause a breakdown in the material. Potential gradient is the ratio of voltage and thickness.
Dielectric strength= V/t= 4/2= 2MV/m.
4. If the dielectric strength of a material is 4MV/m and its potential difference is 28MV, calculate the thickness of the material.
a) 4m
b) 7m
c) 5m
d) 11m
View Answer
Explanation: Dielectric strength is the potential gradient required to cause a breakdown in the material. Potential gradient is the ratio of voltage and thickness.
V/dielectric strength= t= 28/4=7m.
5. If the thickness of the material increases, what happens to the dielectric strength?
a) Increases
b) Decreases
c) Remains the same
d) Becomes zero
View Answer
Explanation: Dielectric strength is the potential gradient required to cause a breakdown in the material. Potential gradient is the ratio of voltage and thickness. Hence as thickness increases, dielectric strength decreases.
6. The thickness of a material having dielectric strength 10MV/m is 5m, calculate the potential difference.
a) 2MV
b) 10MV
c) 50MV
d) 100MV
View Answer
Explanation: Dielectric strength is the potential gradient required to cause a breakdown in the material. Potential gradient is the ratio of voltage and thickness.
V=t*dielectric strength= 5*10=50MV.
7. Which medium has the highest dielectric strength?
a) Water
b) Mica
c) Air
d) Glass
View Answer
Explanation: The better material is to prevent electrical conductivity, higher the dielectric strength. And the air is the best insulator so it has high dielectric strength.
Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.
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