Electricity and Circuits Notes
Current
Current is the flow of electrons.
Measured in amps, which indicates how fast the flow is.
Voltage
Voltage refers to potential difference, which is a change in energy between two points.
Voltage is measured in volts.
Symbol for voltage is V.
Current Symbol
The symbol for current is I.
Potential Difference
Potential difference is provided by a battery.
Batteries contain many electrons, which have negative charges.
Like charges repel each other.
When a wire connects to the electrons in the battery, electrons repel and flow out.
Opposite charges attract.
Electrons flow from negative to positive.
Electrons with negative charges distribute to the light and remove them, then transfer and store them into the battery.
Electromagnetic force drives the movement of electrons due to the attraction of opposite charges.
Electromotive Force (EMF)
A battery creates a force that moves electricity.
Battery = Potential difference = Electromotive force.
Conductors
Copper is the best conductor and is used instead of gold due to cost.
High-end speakers and amplifiers are made of gold.
Series Circuit
Diagrams include symbols for:
Battery
Lamp (or Legacy)
Voltmeter
Voltmeter measures voltage or potential difference.
Requires a difference or change to measure.
Uses two probes to measure the voltage on each side of a circuit component.
The reading indicates the change in voltage across the component.
Example: A 9-volt battery with 3 volts remaining after a light would read 6 volts on the voltmeter (9V - 3V = 6V).
Voltmeters are connected in parallel to the circuit component being measured.
Ammeter
Ammeter measures the flow of charge, or current, in units of amps.
Measures current flow in series, inside the current.
Ohm's Law
Where:
= Current.
= Voltage.
= Resistance.
Resistance in a river (or circuit) slows down the current.
Increased diameter increases flow and decreases resistance.