Voltage, Current and Resistance Flashcards
What is Voltage?
The pressure from an electrical circuits power source
pushes the electrons through the circuit
Higher voltage = higher pressure = more push
What are Voltmeters?
The difference in electrical potential energy between two points in a circuit
AKA the difference between the starting “push” and the ending “push”
AKA: potential difference (how much potential energy there is before and after the load)
How do you measure potential difference?
Voltmeters measure voltage
Voltage (or potential difference) is measured in volts (V)
Have to place a voltmeter in PARALLEL to “hug” the load
Need “push” before and after load
What is current?
The amount of charge passing a point in the circuit per second
# of electrons per second
Higher current = more electrons per second (moving fast)
What is current ( Part 2 )?
If electrons flow in only one direction, it is called direct current (DC) (e.g. Batteries)
If electrons flow back and forth it is called alternating current (AC) (e.g. Electricity from wall sockets)
What are Ammeters?
Measured with an ammeter
Units are amperes (A) or amps
How do you measure current?
Current is the amount of charge passing a point in the circuit per second
To be accurate, all electrons available need to pass through the ammeter
So we have to place an ammeter in SERIES
What is Resistance?
How much a material will slow down the flow of e-
Resistors (substances known to resist electron flow) can be used in circuits to control current or voltage
Higher resistance = slower flow
Less current
How do you measure resistance?
Measured with an ohmmeter
Units are ohms (Ω)
What is the Racetrack Analogy?
Cars = the electrons
Fueling Station = the source
Track = conducting wires
Amount of fuel in gas tank = voltage
Number of cars going by = the current
Speed bumps = the resistance
