Understanding AC and DC Machines

What is the primary function of a DC motor?

• To convert electrical energy into mechanical energy

• To convert mechanical energy into electrical energy

• To store electrical energy

• To regulate voltage

Which component in an AC motor is responsible for producing a rotating magnetic field?

• Stator

• Rotor

• Commutator

• Armature

What is the unit of electrical resistance?

• Ampere

• Volt

• Ohm

• Watt

In a DC machine, what is the purpose of the commutator?

• To increase the current

• To convert AC to DC

• To reverse the direction of current

• To reduce the voltage

What is the frequency of the standard AC supply in Great Britain?

• 50 Hz

• 60 Hz

• 100 Hz

• 120 Hz

Which of the following is a type of DC motor?

• Synchronous motor

• Induction motor

• Series motor

• Stepper motor

What is the formula for calculating electrical power in a DC circuit?

Which of the following materials is commonly used for the core of an electromagnet in motors?

• Copper

• Aluminium

• Iron

• Plastic

What is the main advantage of using an AC motor over a DC motor?

• Higher efficiency

• Simpler construction

• Better speed control

• Lower cost

In an AC circuit, what does the term 'reactance' refer to?

• Resistance to direct current

• Opposition to change in current

• Voltage drop across a resistor

• Power loss in the circuit