Ohm’s Law

Calculating Current, Voltage, and Resistance

SC Physical Science Standards

PS-6.6 Explain the relationships among voltage, resistance, and current in Ohm's law. 

PS-6.7 Use the formula V = IR to solve problems related to electric circuits.

VoltageCurrent

Resistance

Voltage Difference- the ‘push’ that causes charges to move

An electric charge has electrical potential energy.

The closer one charge is to another, the more energy they have to push or pull on each other.

Measured in volts (V).

When a battery is connected, it is voltage that pushes and pulls the electrons through the wire to the other end of the battery.

The flow of electrons through a conductor.

Measured in amperes or amps (a).

Represented by I in the formula.

When a material opposes the flow of electric charges.

This happens when electrons flowing through a wire run into things in the wire and bounce around.

Measured in Ohms (Ω). Represented by R in the formula.Things that affect resistance:

Type (what it is made of)Temperature (increase temp,

increase motion) Length (longer wire = further distance) Thickness (diameter of the wire)

Measuring Voltage, Current, and Resistance

Volt-meter- device to measure voltage

Ammeter- device to measure current

Ohm-meter- device to measure resistance

Ohm’s Law states that the current in a circuit is directly proportional to the voltage in the circuit, and is inversely proportional to the resistance in the circuit.

If the voltage increases and resistance stays the same, current will increase.

If the voltage stays the same and the resistance increases, current will decrease.voltage

resistanceCurrent =

I = CurrentR = Resistance

V

I R

V = Voltage

VI

R =

Looking for resistance ?

VI

R=

Looking for current ?

IV R= XLooking for voltage ?

The End!