Unit 1: Topic 1: Alternating Current and Voltage Flashcards
What is all matter made up of?
Protons, neutrons and electrons.
The _____ charged protons and attracted to the _____ charged electrons.
positively, negatively.
What is the overall charge of an atom?
Zero.
In an atom, the number of _____ must equal the number of electrons.
protons.
What is an electric charge measure in?
Coulombs, C.
What is the definition of an electric current?
It’s the measure of the flow of charge around a circuit and depends on the amount of charge passing any point in a circuit every second.
What is electric current measured in?
Amperes, A.
What is electric charge measured in?
Coulombs, Q.
A battery supplies a ____ e.m.f.
Constant.
Why does a battery supply a constant e.m.f?
It’s so the current is always in the same direction.
What does d.c stand for?
Direct current.
What does a.c stand for?
Alternating current.
What are transformers essential for?
To step voltages up or down for the transmission of electrical energy.
In transformers, less energy is dissipated as heat in the cables when a high ____ and so a _____ current is used to transmit electrical ____.
voltage, smaller, energy.
In an a.c supply, what are the maximum values called?
Peak values, Vp.
In an a.c supply, the peak to peak values are ___ the peak value, Vpp.
twice.
On an a.c waveform, does the e.m.f change amplitude?
Yes, constantly.
What is the equation used for the period of a wave?
T=1/f.
What is a Cathode Ray Oscilloscope used for?
It’s an extremely versatile device which is used to measure a.c and d.c voltages. It can also measure a.c signals.
Voltages to be measured are connected to the _ plates of the CRO which have a _____ gain which affects the Y ______.
Y, variable, sensitivity.
When measuring frequency using a CRO, what does the time base control do?
Changes the time which the spot takes to move horizontally across the screen.
When measuring frequency using a CRO, what is the time base used for?
To find the frequency of an a.c wave.
What is the definition of frequency?
The number of cycles (waves) in 1 second.
What is the equation used for frequency?
Frequency = 1/time for 1 wave.
What is frequency measured in?
Hertz (Hz).
What is time measured in ?
Seconds (s).
What does Hz equal too?
s^-1.
What is the definition of the rms?
The a.c voltage which produces the same heating effect as a d.c voltage.
What does rms stand for?
Root mean squared voltage.
What does the word ‘mean’ in rms represent?
Average.
