What are motors?
Devices that convert electrical energy into rotational mechanical energy.
What are generators?
Devices that convert rotational mechanical energy into electrical energy.
What is a commutator?
A metal strip on the outside of the shaft that provides electrical conductivity from the rotating shaft to the coils on the rotor.
What is a brush?
A conductive component that maintains electrical contact with rotating parts in electric machines.
How can you change the polarity of a magnet?
By reversing the direction of current in an electromagnet or by physically flipping a permanent magnet.
What is efficiency?
The ratio of useful output power to input power, expressed as a percentage.
Write the efficiency equation.
Efficiency = P_out / P_in × 100%
How is heat modeled in electric machines?
As copper losses due to I²R.
Write the copper loss equation.
P_loss = I²R
What are examples of core losses in a motor?
Magnetic flux leakage.
What are examples of mechanical losses in a motor?
Friction, windage, and bearing losses.
What is base power in power generation?
The minimum level of power that a generation system must supply continuously.
What is intermediate power in power generation?
Power generated to meet demand between base load and peak load; this is the predictable increase.
What is peak power in power generation?
The maximum output power a generation system can produce under specific conditions.
What is Ampère’s Law?
The magnetic field around an electric current is proportional to the electric current that produces it.
What is Faraday’s Law?
A changing magnetic field within a closed loop induces an electromotive force (EMF) in the loop.
Why do we increase voltage for power transmission?
To reduce power loss due to resistance in transmission lines; volts up, current down.
Write the transmission line power loss equation.
P_loss = I²R
What is the primary side of a transformer?
The side of the transformer that receives the input voltage.
What is the secondary side of a transformer?
The side of the transformer where the output voltage is taken.
What material is used between transformer windings?
A ferrous material such as iron to direct the magnetic field between the coils.
What is the name of the force induced in a transformer?
Electromotive force (EMF).
What is a step-up transformer?
A device that increases voltage while decreasing current.
What is a step-down transformer?
A device that decreases voltage from primary to secondary while increasing current.
What is turns ratio?
The ratio of the number of turns in the primary coil to the number of turns in the secondary coil.
Write the transformer voltage ratio equation.
V_p / V_s = N_p / N_s
Write the transformer current ratio equation.
I_p / I_s = N_s / N_p
Write the ideal transformer power relationship.
P_p = P_s
