Basic Electrical Engineering Multiple Choice Questions on “Dielectric Strength”.
1. The unit for dielectric strength is ____________
A. V/m2
B. MV/m2
C. MV/m
D. Vm
Answer: C
Clarification: 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
Answer: A
Clarification: 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
Answer: A
Clarification: 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
Answer: B
Clarification: 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
Answer: B
Clarification: 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
Answer: C
Clarification: 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
Answer: C
Clarification: 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.