WorksheetsUnderstanding DC and AC Motors
Total questions: 20
Worksheet time: 10mins
Which of the following is a main component of a DC motor?
Commutator
Slip rings
Transformer
Capacitor
What is the primary function of the armature in both DC and AC motors?
To supply electrical power
To rotate and produce mechanical work
To cool the motor
To store energy
Which part is unique to the construction of an AC motor compared to a DC motor?
Brushes
Commutator
Slip rings
Permanent magnet
What is the working principle of a DC motor?
Electromagnetic induction
Fleming’s left-hand rule
Faraday’s law of electromagnetic induction
Lenz’s law
In an AC motor, what causes the rotor to turn?
Direct current supplied to the armature
Rotating magnetic field produced by alternating current
Permanent magnets only
Mechanical force applied externally
Which of the following best describes the main difference in the phenomenon between DC and AC motors?
DC motors use alternating current, AC motors use direct current
DC motors use a commutator, AC motors use slip rings
Both use the same type of current
Both use slip rings
Which of the following is NOT a typical application of a DC motor?
Electric trains
Ceiling fans
Electric vehicles
Cranes
What is the main advantage of using an AC motor in household appliances?
High starting torque
Simple construction and low maintenance
Requires a commutator
Runs only on batteries
Which component in a DC motor reverses the direction of current in the armature winding?
Slip rings
Commutator
Stator
Rotor
What type of current is supplied to the stator of an AC motor?
Direct current
Alternating current
Pulsed DC
Static current
Which law is primarily used to explain the force experienced by a conductor in a magnetic field in a DC motor?
Ohm’s law
Fleming’s left-hand rule
Newton’s law
Joule’s law
Which of the following is a common use for AC motors?
Battery-powered toys
Industrial pumps
Portable fans
Mobile phones
What is the main function of brushes in a DC motor?
To provide insulation
To supply current to the rotating armature
To cool the motor
To increase speed
Which of the following statements is true about the construction of AC motors?
They always have a commutator
They use slip rings instead of a commutator
They do not have a rotor
They require brushes for operation
Which type of motor is generally preferred for applications requiring variable speed and high starting torque?
AC motor
DC motor
Synchronous motor
Stepper motor
What is the main reason AC motors are widely used in industry?
They are more expensive
They are easier to control
They are robust and require less maintenance
They need frequent brush replacement
Which of the following is NOT a difference between DC and AC motors?
Type of current used
Use of commutator or slip rings
Both have the same working principle
Applications
In which application would you most likely find a DC motor?
Washing machine
Electric car
Refrigerator
Air conditioner
Which of the following best describes the working principle of an AC motor?
Direct current creates a static magnetic field
Alternating current creates a rotating magnetic field
Commutator reverses current direction
Permanent magnets rotate the shaft
What is the main role of the stator in both DC and AC motors?
To rotate and produce mechanical work
To provide a stationary magnetic field
To reverse the direction of current
To store electrical energy
