WorksheetsRME Review - Capacitor
Total questions: 38
Worksheet time: 19mins
The starting capacitor of a single-phase motor is generally a/an _______________ capacitor
electrolytic
paper
ceramic
metal
A capacitor has a capacitance of 5 F connected to a 6 Volts supply voltage. Find the value of the charge stored in the capacitor?
30 Coulombs
30 Ampere
30 Volts
30 ohms
A 4 F capacitor carries a charge of 2.5 C. What is the potential difference across the plates of the capacitor?
0.5 Volts
0.625 Volts
1.25 Volts
2.25 Volts
How does a capacitor store energy?
In the form of a magnetic field
In the form of an electric field between two plates
In the form of heat
By converting AC to DC
What is the primary function of a capacitor in single phase motor?
for starting
for converting AC to DC
for improving efficiency
for changing the speed
What type of capacitor is commonly used in electronic circuits due to its small size and stability?
ceramic
electrolytic
metal
supercapacitor
Why do electrolytic capacitors have polarity?
They are designed for AC circuits only
Their dielectric material is sensitive to reverse voltage
They are used only in transformers
They store energy magnetically
What is the role of a capacitor in a rectifier circuit?
To convert AC to DC
To filter and smooth DC output
To increase resistance
To amplify the signal
What happens if two capacitors are connected in series?
The total capacitance decreases
The total capacitance increases
The voltage across each capacitor becomes zero
The capacitors act as resistors
What happens if two capacitors are connected in parallel?
The total capacitance increases
The total capacitance decreases
The voltage across each capacitor increases
The capacitors short-circuit each other
Which of the following is a common application of capacitors?
Voltage regulation in power supplies
High-speed data transmission
Reducing motor efficiency
Increasing inductance in transformers
What safety precaution should be taken before handling a high-voltage capacitor?
Ground the capacitor to discharge stored energy
Short-circuit the capacitor terminals with a screwdriver
Wash the capacitor with water
Use a multimeter to measure resistance before touching
In a three-phase motor, where is the power factor correction capacitor typically installed?
In series with the motor windings
In the neutral connection of the motor
In series with the motor shaft
Parallel to the power supply terminals
What effect does increasing the plate area of a capacitor have on its capacitance?
It decreases the capacitance
It increases the capacitance
It has no effect on the capacitance
It decreases the voltage rating
Which capacitor characteristic determines how much voltage it can safely handle?
voltage
resistance
frequency
torwue
When the voltage across a capacitor is doubled, how does the stored energy change?
It remains the same
It doubles
It quadruples
It halve
A capacitor with a capacitance of 100 F is charged to 50V. How much energy is stored in it?
125 kW
12.5 kW
1.25 kW
12,500 kW
Which factor does NOT affect the energy stored in a capacitor?
Capacitance
Voltage
Dielectric constant
Resistance in the circuit
What happens to the power in an ideal capacitor over a full AC cycle?
It is continuously dissipated
It is lost as heat
It averages to zero
It doubles
Why is the power dissipated in an ideal capacitor zero?
Because a capacitor blocks DC current
Because they have infinite resistance
Because capacitors only store and release energy, not dissipate it
Because they are made of dielectric material
An inductor of 50 mH carries a current of 2A. How much energy is stored in it?
0.05 Joules
0.1 Joules
0.2 Joules
0.5 Joules
Which factor does NOT affect the energy stored in an inductor?
Inductance
Current
Resistance
Magnetic field
What happens to the power in an ideal inductor over a full AC cycle?
It is continuously dissipated
It is lost as heat
It averages to zero
It doubles
A 0.5 H inductor carries a current of 4A. How much energy is stored in it?
2 J
3 J
4 J
20 J
What is the primary function of an inductor in an electrical circuit?
To increase voltage
To store energy in a magnetic field
To filter AC signals
To convert AC to DC
How does the frequency of an AC signal affect the reactance of an inductor?
It has no effect
It decreases reactance
It increases reactance
It doubles the reactance
What is the unit of measurement for capacitance?
Henry
Volt
Farad
Ohm
Which material is most commonly used in semiconductor components?
silicon
copper
aluminum
gold
How does a diode function in an electrical circuit?
It allows current to flow in both directions
It blocks current flow in all conditions
It allows current to flow in one direction only
It amplifies current
What type of semiconductor device is used to control high-power AC loads?
Diode
Thyristor (SCR)
resistor
transformer
In an electrical panel, where might you find semiconductors?
circuit breakers
contactors
VFD
grounding rods
Which semiconductor device is commonly used for rectification in power supplies?
triac
diodes
transformer
inductor
In a three-phase motor drive system, how are semiconductors used?
They help in mechanical alignment
They act as thermal insulators
They regulate voltage and current through switching devices like IGBTs
They increase the physical size of the motor
What is the purpose of a Zener diode ?
To store energy
To allow current to flow in both directions
To provide surge protection
To increase current flow
Why are IGBTs (Insulated Gate Bipolar Transistors) used in VFDs?
They provide efficient, high-speed switching for AC motor control
They generate resistance in circuits
They increase the weight of the motor
They prevent current from flowing
How many valence electrons does semiconductors have?
4
8
2
0
What happens when a semiconductor junction is forward biased?
It blocks current flow
It allows current to flow
It amplifies voltage
It stores charge
How does the resistance of a semiconductor change with an increase in temperature?
It remains constant
It decreases as temperature increases
It increases as temperature increases
It fluctuates randomly
