hw 3

Which of the following explains the basic operating principles of a motor?

• A motor converts electrical energy into mechanical energy.

• A motor converts mechanical energy into electrical energy.

• A motor stores electrical energy for later use.

• A motor is used to measure electrical energy.

What are the three factors that determine the amount of force exerted on a current-carrying conductor to move when placed in a magnetic field?

• Current, magnetic field strength, and length of the conductor

• Voltage, resistance, and temperature

• Frequency, amplitude, and wavelength

• Mass, velocity, and acceleration

Motors are classified into different types. Which of the following is a type of motor?

• Induction motor

• Combustion engine

• Hydraulic pump

• Steam turbine

a. The direction of rotation of a permanent-magnet DC motor is changed how? b. The speed of a permanent-magnet motor is controlled how?

• a. By reversing the polarity of the supply voltage; b. By varying the supply voltage

• a. By changing the motor windings; b. By using a gearbox

• a. By adjusting the brush position; b. By changing the load

• a. By using a rheostat; b. By altering the magnetic field

What are the three types of electromagnetic DC motors?

• Series DC motor, Shunt DC motor, Compound DC motor

• Induction motor, Synchronous motor, Stepper motor

• Brushless DC motor, Servo motor, Universal motor

• Linear motor, Reluctance motor, Hysteresis motor

What’s the function of the commutator in relation to the operation of DC motors?

• To reverse the direction of current in the motor windings

• To increase the speed of the motor

• To decrease the voltage supplied to the motor

• To provide lubrication to the motor parts

Compare DC series with DC shunt motors in relation to starting torque and speed regulation.

• DC series motors have higher starting torque and poorer speed regulation compared to DC shunt motors.

• DC shunt motors have higher starting torque and poorer speed regulation compared to DC series motors.

• Both DC series and DC shunt motors have similar starting torque and speed regulation.

• DC series motors have lower starting torque and better speed regulation compared to DC shunt motors.

A decrease in shunt field current affects the speed of the motor in a DC shunt motor by:

• Increasing the speed

• Decreasing the speed

• Having no effect on the speed

• Causing the motor to stop

Which type of DC motor is made basically the same as the universal motor?

• Series DC motor

• Shunt DC motor

• Compound DC motor

• Permanent magnet DC motor

The universal motor can operate from either a DC or AC source because:

• It has a commutator and brushes that allow it to work with both types of current.

• It is designed to work only with DC current.

• It uses a transformer to convert AC to DC.

• It has a built-in inverter for AC operation.