1. Electricity

2. Electricity is the flow of electrons along a given path

3. Protons have a (+) charge and are found in the nucleus
Electric Charge
Atoms are made up of charged particles
Protons have a (+) charge and are found in the nucleus
Electrons have a (-) charge and are free to move around the atom

4. Behavior of Charges
Opposite charges attract
Like charges repel

5. Conductors Electric charges are free to move from atom to atom
within a material
Caused by weak
attraction between
nucleus and electrons

6. Insulators Resist the flow of electrons from atom to atom
within a material
Caused by strong
attraction between
nucleus and electrons

7. Conducting Ability

8. Current
Amount of charge that flows through a circuit in a given amount of time
Measured in amperes (amps) (A) by an ammeter
Determines the brightness of a light bulb

9. Current Flow in a Circuit
Electrons are what
are moving to
cause electricity
In a circuit,
current flows from
(+) end of battery
to (-) end

10. Voltage (Potential Difference)
Amount of electric potential energy per unit of charge
Measured in Volts (V) by a voltmeter
Determined by the energy source (battery)

11. Battery/Electrochemical Cell
Converts chemical energy into electrical energy
Current flows from high potential energy to low potential energy
(+) end = high electrical potential
(-) end = low electrical potential

12. Resistors
Opposes the current flow in a circuit
Measured in Ohms ()
Any device that uses energy within a circuit – a light bulb, a motor, etc.

13. Ohm’s Law
Voltage = Current x Resistance
V = I x R
Voltage (V) has a direct relationship with current (I) and resistance (R)
Current (I) and resistance (R) have an indirect relationship

14. Circuits
Circuits are closed loops through which charges can travel

15. Circuit Symbols
Wire _____
Resistor
Closed switch
Open switch
Battery

16. Circuits

17. Types of Circuits: Series and Parallel

18. Series Circuits Have a SINGLE path for current to flow
The current is the same in every resistor
The sum of the voltage across the individual resistors is equal to the voltage of the battery.
The total resistance (Req) is equal to the sum of the individual resistance values
If one bulb goes out, all bulbs go out.

19. Applying Ohm’s Law to Series Circuits
1. Add up all resistance values to find the total resistance Req (equivalent resistance)
2. Use Req & the battery’s voltage in Ohm’s law to find the total current of the circuit.
This is the same current that travels through each resistor!
3. Use the resistance & current in Ohm’s law to find the Δ V across the resistor

20. Use the information provided to solve for the missing variables in the circuit
R1 = 17 R2 = 12 R3 = 11 ΔV = 60V
Find: Req = Itot =
I1 = ΔV1 =
I2 = ΔV2 =
I3 = ΔV3 =

21. Use the information provided to solve for the missing variables in the circuit
R1 = 11 R2 = 7 R3 = 20 ΔV = 19V
Find: Req = Itot =
I1 = ΔV1 =
I2 = ΔV2 =
I3 = ΔV3 =

22. Parallel Circuits Have multiple paths (branches) for current to flow
The voltage is the same across every resistor.
The sum of the current in each individual branch is equal to the current outside the branches.
The total resistance is found using:
1/Req = 1/R1 + 1/R /R3 …
If one bulb goes out, the rest remain lit.

23. Applying Ohm’s Law: Parallel Circuits
1. Add up all resistance values (1/R) to find the total resistance Req (equivalent resistance)
2. Use Req & the battery’s voltage in Ohm’s law to find the total current of the circuit.
3. Use the resistance & ΔV of each resistor in Ohm’s Law to find the current.
Remember voltage is the same throughout the circuit.

24. Use the information provided to solve for the missing variables in the circuit.
R1 = 17 R2 = 12 R3 = 11 ΔV = 60V
Find: Req = Itot =
I1 = ΔV1 =
I2 = ΔV2 =
I3 = ΔV3 =

25. Use the information provided to solve for the missing variables in the circuit.
R1 = 11 R2 = 7 R3 = 20 ΔV = 12V
Find: Req = Itot =
I1 = ΔV1 =
I2 = ΔV2 =
I3 = ΔV3 =