Intro to electricity

APES 2024

Scientists have only known about electricity for about

Scientists have only known about electricity for about

100 years

In the center of every atom is a

nucleus with a positive electrical charge, around it is electrons with a negative charge

Positive and negative charges attract, and it's this

electromagnetic force that holds the atom together

Electricity happens when

electrons to line up and all flow together

The most common way we make electrons move is by

pushing them with magnets (bc electrons are charged particles, they’re like magnets, and they can be pulled towards or pushed away from other magnets)

To get just one ampere of electricity

requires over six quintillions of electrons all flowing per second

Ampere

the unit uses to measure the flow of electrons

Voltage (V)

the pressure that pushes electrons in a circuit (a measure of the strength of the current in a circuit and measured in volts (V))

Voltage ex.

• AA batteries are 1.5 volts; they apply a small amount of voltage or pressure for lighting small fashlight bulbs

• A car usually has a 12-volt battery—it applies more voltage to push current through circuits to operate the radio or defroster

• standard voltage of wall outlets is 120 volts—a dangerous amount of voltage

• electric clothes dryer is usually wired at 240 volts—a very dangerous voltage

Electric current (I)

the number of electrons fowing past a fxed point, defned as electrons fowing between two points having a diference in voltage, measured in amperes or amps (A) (One ampere is 6.25 X 1018 electrons per second passing through a circuit)

As the cross-sectional area of the wire increases, so does the

amount of electric current (number of electrons) that can fow through it

Resistance (R)

a property that slows the fow of electrons, depends on the metal the wire is made of and its diameter, measured in ohms (Ω) (copper, aluminum, and silver—metals used in conducting wires—have diferent resistance)

Resistors

has a set resistances, that can be placed in circuits to reduce or control the current fow

Load

any device placed in a circuit to do work (ex. light bulb in a fashlight, television plugged into a wall outlet)

Every load has

resistance

Ohm’s Law

the current that fows through a material is proportional to the voltage, if doubled in voltage, the current also doubled, if reduced the voltage by half, the current dropped by half. The resistance of the material remained the same

George Ohm

a German physicist, discovered that in many materials, especially metals, the current that fows through a material is proportional to the voltage (Ohm’s Law)

Ohm’s Law formulas

• Voltage = current x resistance V = I x R or V = A x Ω

• Current = voltage / resistance I = V / R or A = V / Ω ƒ

• Resistance = voltage / current R = V / I or Ω = V / A

Electric power formula

Power = voltage x current P= V x I or W = V x A

Power (P)

measure of the rate of doing work or the rate at which energy is converted

Electric power

the rate at which electricity is produced or consumed (the amount of electric current fowing due to an applied voltage) (the amount of electricity required to start or operate a load for one second, measured in watts (W))