This lesson covers parallel and series circuits. A series circuit has one path for current to flow and the same current passes through each component. In a parallel circuit, there are multiple paths for current and the total current is the sum of the branch currents. The document also discusses electricity in homes, including how alternating current works and safety devices like fuses and circuit breakers that prevent overloads. Key terms defined include joules, watts, kilowatt-hours, and equations for power.

1. Lesson 7:
Parallel and
Series Circuits

2. Learning Goals
We will be learning to…

3. Success Criteria
By the end of this class, I will be able to…

4. Series
Circuit
01
You can enter a subtitle here if you need it

5. Series Circuits
• Only one path for current to flow
• The current is the same in all parts
of the circuit.
IT = I1 = I2 = I3…
• Therefore, the number of coulombs
passing
• through each load is the same.
• If the circuit is broken at any point,
then the current flow stops.

6. Series Circuits
• Since the current flows
through all loads, electrons
lose energy as they pass
through each load.
• The potential difference
(voltage) is split between
the loads in the circuit.
Therefore,
VT = V1 + V2 + V3 …

7. Series Circuit
• The resistance increases with each load.
RT = R1 + R2 + R3 …
• The power increases with each load
PT = P1 + P2 + P3 …
(same as in parallel)

8. Parallel
Circuit
02
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9. Parallel Circuits
• There is more than one path for the current to flow through
• Current is NOT the same at different points. The current (the
electrons) is shared by as many paths as there exist.
• Current flowing from the energy source equals the sum of all the
separate branch currents in the circuits.
IT = I1 + I2 + I3 …
• I, in each path, depends on the size of the resistor.
• The more resistors, there are in the circuit, the more “pull” for
energy and the greater the current.*

10. Parallel Circuit
• If any one device is removed, it
does not affect the others.
• Each branch circuit is
connected directly across the
battery, therefore has the
identical potential difference
as there is across the battery.
VT = V1 = V2 = V3 …

11. Parallel Circuit
• Adding resistance in parallel, decreases the total
resistance of the circuit.
RT = 1/R1 + 1/R2 + 1/R3 …
• The power is calculated as follows:
PT = P1 + P2 + P3 …
(the same as in series)

12. Electricity in
the home
03

13. Two Types of Current
●Direct current – electrons always travel in one direction as in batteries and cells.
●Alternating current – electrons go back and forth rapidly sixty times per second.
●This allows for efficient distribution of high voltage electricity via transformers
that increase (step up) or decrease (step down) the potential difference of power
lines as it gets closer to your home or school

14. Fun Fact
● Do you know who invented
alternating current?
● Nikola Tesla

15. Electricity in the home
●For practical three wires enter our homes:
●1 white (neutral – 0 Volts)
●1 red (+120 Volts)
●1 black (-120 Volts)

16. Electricity in the home
• If too much current flows through a wire, it overheats which can lead
to a fire. Fuses and circuit breakers detect dangerous current
overloads.
• FUSES – a thin wire that melts at a pre-determined current level so as
to break the circuit. Must be replaced with a new fuse.
• CIRCUIT BREAKER – a heat sensitive switch that “trips” off when
current overheats the wire. Can be reset by flipping the switch.

17. Electricity in the home
• In your home, a digital or dial meter reads the electric
current used in kilowatt-hours
(1 kW•h = 1000 watt hours).

18. Measurements
●WHAT’S A JOULE?? A JOULE (J) is the unit for ENERGY
●WHAT’S A WATT?? A WATT (W) is the unit for power - a kilowatt (kW) is one
thousand watts
( 1.0 kW = 1000 W)
●POWER POWER MEASURES “HOW FAST” YOU USE ENERGY – THE
EQUATION FOR POWER IS
OR

19. Unit of energy
●THE kWh as a UNIT OF ENERGY ( hint: get “E” by itself in the power equation)

20. Find the total cost of this sample
electricity bill and answer the
questions