This set of Basic Electrical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Leakage and Conduction Currents in Capacitors”.
1. Leakage in capacitors is primarily caused by _________
a) Transistors
b) Resistors
c) Inductors
d) DC motors
View Answer
Explanation: Leakage is primarily caused due to electronic devices, such as transistors, connected to the capacitors. Transistors conduct a small amount of current even when they are turned off, hence they are responsible for leakage current.
2. What is the conduction current when a capacitor is fully charged?
a) Infinity
b) Zero
c) 100A
d) 1000A
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Explanation: When a capacitor is fully charged, there is no conduction of electrons from one plate of the capacitor to another, hence there is no conduction current and conduction current is equal to zero.
3. The flow of electrons in dielectric is due to _________
a) Conduction
b) Potential difference
c) Breakdown
d) Resistance
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Explanation: There is, under normal circumstance, no flow of electrons in a dielectric since a dielectric is basically an insulator. Hence, there is a flow of electrons in a dielectric only at breakdown voltage.
4. The flow of electrons which does not pass through the battery is known as ________
a) Displacement current
b) Leakage current
c) Either displacement or leakage current
d) Neither displacement nor leakage current
View Answer
Explanation: Displacement current is the flow of electrons from the positive plate of the capacitor to the negative plate of the capacitor, not through the battery. Hence the type of current which flows without passing through the battery is displacement current.
5. The free electrons in practical dielectrics is due to _________
a) There are no free electrons
b) Conductors
c) Impurities
d) Both conductors and impurities
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Explanation: Ideally, dielectrics are insulators and do not contain any free electrons. But no dielectric is a perfect dielectric, hence the free electrons are due to impurities present in each dielectric.
6. The current in conductors connecting the voltage source to the plates of a capacitor is ______
a) Conduction current
b) Leakage current
c) Charging current
d) Zero
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Explanation: The current in conductors connecting the voltage source to the plates of a capacitor is the charging current and not the conduction or leakage current.
7. What is the type of current where the electrons actually move?
a) Displacement current
b) Conduction current
c) Both conduction and displacement current
d) Neither conduction nor displacement current
View Answer
Explanation: Conduction current is the current caused by the actual flow of electrons and displacement current is the current where no charge carriers are involved.
8. What is the type of current caused due to variations in the field?
a) Displacement current
b) Conduction current
c) Both conduction and displacement current
d) Neither conduction nor displacement current
View Answer
Explanation: Displacement current is the current where no charge carriers are involved. It is caused due to variations in the electric field.
9. Under normal conditions capacitors have _________
a) Displacement current
b) Conduction current
c) Both conduction and displacement current
d) Neither conduction nor displacement current
View Answer
Explanation: Under normal conditions capacitors contain an insulating material called dielectric sandwiched between the plates of the capacitor. Since insulators can carry only an electric field but not moving carriers, therefore normally a capacitor has displacement current and not conduction current.
10. If a large amount of voltage is applied to a capacitor, what is the current that flows through it?
a) Displacement current
b) Conduction current
c) Both conduction and displacement current
d) Neither conduction nor displacement current
View Answer
Explanation: When a large amount of voltage is applied between the plates of a capacitor, the dielectric between the plates does not behave as an insulator anymore and starts conducting and conduction currents flow through it.
Sanfoundry Global Education & Learning Series – Basic Electrical Engineering.
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