Electricity and Magnetism

There negative and positive charges. If something has a negative charge,

that means it has more electrons than protons. If something has a positive

charge then it has more protons. A charge can gain and lose electrons, but

not protons. A neutral charge means the object has equal amount of protons

and electrons.

Charges that are the same repel so a positive and positive charge will repel.

Opposite charges attract, so negative and positive charges will attract.

In circuits,

We have Ohm's Law: Voltage= current x resistance

Voltage(V) is in the units of volts (V), current (I) is in amps (A), and resistance(R)

in ohms (Ω)

Current is the flow of charge

Power= current x voltage

In a series circuit, the current is always the same in all wires. The resistors add up to the total resistance.

Light bulbs have resistors, so more light bulbs in a series circuit then the lights will be dim as the

total resistance increases. So the voltage = total resistance*current ...Ohm's Law.

If one light bulb goes out, all of the light bulbs go out.

In a parallel circuit, the currents add and the voltage is the same at all places.

The inverse of the resistors add up. So when you add light bulbs in parallel

they will get brighter as the total resistance decreases.