1. Current, Voltage, and Resistance in a circuit

2. Characteristics of a circuit
V is voltage (volts – V)
I is current (amperes or amps – A)
R is resistance ( ohms - Ω)

3. Voltage
Also called Potential (don’t confuse this with potential energy)
Voltage is the Energy per Coulomb provided to the circuit.
Potential differences are what drive current in a circuit

4. Voltage
Measured in volts

5. How batteries create a voltage difference

6. Current Current is the rate at which charges flow through a circuit
1 coulomb in 1 sec = 1 Ampere (Amp)

7. Direction of the Current flow
CONVENTIONAL CURRENT
Direction positive charges would move
Away from higher potential (+ on the battery)
ELECTRON CURRENT
Direction electrons would move
Away from lower potential (- on the battery)

9. Resistance
The electrons encounter obstacles as they move through a circuit (this is what creates resistance to the current)
Measured in ohms Ω

10. Resistance Resistance depends on three properties
Material (resistivity 𝜌 )
Cross-sectional area
length

11. In Summary

12. Voltage in a circuit
When voltage sources are connected in series and in the same direction, their voltages add together.
If they’re in opposite directions you subtract their voltages (it’s like they’re working against each other)

13. Resistance in a circuit
In a series circuit, you add each of the individual resistances

14. In a parallel circuit, it’s a little more complex.

15. Chanting Ohmmmmm on the AP exam has not been proven to be effective.
Current in a circuit
The amount of current flowing through a given part of a circuit is determined from the resistance and the voltage using ohm’s law
Chanting Ohmmmmm on the AP exam has not been proven to be effective.

16. Ohm’s Law V = IR V is voltage (volts – V)
I is current (amperes or amps – A)
R is resistance ( ohms - Ω)

17. Determining Voltage, Resistance, and Current in a circuit

18. That’s great if you have a purely series or parallel circuit but what if there’s a combination of the two, some kind of, I don’t know, “combination circuit”?

20. SOLVING THE COMBINATION CIRCUIT

21. The basic strategy is to simplify the circuit into a series circuit.

26. Power The power dissipated in a circuit element equals: P=IV
The total power dissipated by the elements in a circuit must equal the power supplied by the battery
Basically you have to use all the power and you can’t use more power than you’re given