Ac theory Flashcards
What type of current is driven by an EMF with a positive +ve potential at one end and a negative -ve potential at the other end?
Direct current
What type of current exists when the current travels first in one direction and then in the other?
Alternating current
True or False: When power is transmitted over long distances, losses occur due to the resistance of the cables and the size of the current being carried.
True
What equipment is used to change the relative size of the voltage and current without appreciable loss?
Transformers
Will a transformer work on direct current?
No
List two advantages of AC over DC.
Use of transformers, equipment can be lighter.
In which direction does AC travel through a conductor?
forwards and backwards
What is the speed at which AC changes direction called?
frequency
What do we call the level to which voltage or current rises in an AC waveform?
amplitude
True or False: In both AC and DC systems, currents are measured in amperes.
True
True or False: One complete cycle of an AC sine wave is one complete revolution of the generator.
true
When has one cycle been completed in the diagram of a sine wave
When the wave completes movement in both directions.
What is the AC wave called if it is sinusoidal?
sine wave
How is the frequency of an AC wave generally known?
Hertz(Hz)
What is the term for the time taken to complete one cycle?
frequency
What is the frequency formula?
Frequency = 1 / Time
What is the term for the value of voltage at any given point in the sine wave?
amplitude
What value reaches its maximum value in both positive and negative half cycles?
Peak value
Typically, how do we refer to the supply voltage, phases, and current on ships?
3-phase 450V, 60Hz
