# Electricity ```Electricity
• A neat analogy to help understand these
terms is a system of plumbing pipes. The
voltage is equivalent to the water
pressure, the current is equivalent to the
flow rate, and the resistance is like the
pipe size.
• Energy Vampires (2:38)
Charge
• whether two charges attract or repel depends
on whether they have the same or opposite sign
• unit of measurement for charge is the coulomb
(C)
– one electron has a charge of
0.00000000000000000016 coulombs
Current
• comes from the motion of electrons
• is the rate at which electrons flow past a point
on a circuit
– measured in units called amperes, or amps (A)
current
Voltage
• a measure of electric potential energy
• voltage is an electrical force
– measured in volts (V)
• a difference in voltage provides the energy that
causes current to flow
Resistance
• the resistance to the flow of electrical current
– measured in ohms
• the resistance of electricity creates heat
Circuits
• current only flows when there is a complete
and unbroken path, or a closed circuit
• Electricity and Circuits (8:35)