2365 602 RJH2

What is the primary purpose of a commutator in a DC motor?

• To reduce noise
• To increase efficiency
• To reverse the direction of current
• To generate magnetic fields

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

• Resistance to current
• Opposition to change in voltage
• Opposition to change in current
• Total impedance

Which material is generally used for the core of a transformer?

• Copper
• Aluminium
• Steel
• Brass

What is the function of a thyristor in an electrical circuit?

• Amplify signals
• Act as a switch
• Store energy
• Measure current

Which law determines the direction of induced current in a conductor?

• Ohm's Law
• Ampere's Law
• Lenz's Law
• Faraday's Law

What is the phase difference between voltage and current in a purely capacitive circuit?

• 0 degrees
• 45 degrees
• 90 degrees
• 180 degrees

In a synchronous motor, what is 'hunting'?

• Sudden speed increase
• Oscillation around synchronous speed
• Constant speed operation
• Speed reduction

How many electrons are there in the outer shell of a good conductor?

• 1
• 2
• 3
• 4

What is the typical efficiency range of a modern transformer?

• 50-60%
• 60-70%
• 70-80%
• 95-98%

What does the term 'power factor' represent in an electrical circuit?

• Voltage to current ratio
• Efficiency of power usage
• Phase difference between voltage and current
• Total power consumed