1. Aim: How do we analyze a series circuit?
HW: Problem Set

2. Combine Ohm’s Law and Power Law Recall earlier equation for power…
Power Equations
Combine Ohm’s Law and Power Law
Recall earlier equation for power…
Relate to POWER Rangers… get it? Because they are POWER and morph… like equations… yea.

3. Circuit Types
Draw a standard simple circuit with all the pieces that make it tick.
What’s strange about this diagram?
Conventional current

4. Conventional Current
The direction that positive charge would flow equal to electron flow.

5. Circuit
A path through which current flows from an area of high voltage to an area of low voltage. How does this make sense?
From electrostatics:
Negative charges flow from low to high potential.
Positive charges flow from high to low potential.
Conventional current is a measure of positive charge flow, which goes high to low!

6. Circuit Element Review
Other Elements
Resistances
Measurement Devices
Voltage sources
Fixed resistor – resistance
does NOT change once installed
Opens and closes the circuit turning
current flow on or off
Resistance CAN be changed after installation
Voltmeter is a device
for measuring
VOLTAGE
How hard are electrons
being pushed?
Ammeter is a device
for measuring CURRENT
How many electrons
flow per second?
Provide electrical potential for electrons – “PUSHING”
or “PUMPING” them through the circuit
Special resistor – used to produce light!

7. Measurements V V V A A V 100V R = 10Ω 0V 0V 10A 10A Voltmeter measures
RELATIVE
differences
from OUTSIDE
the circuit
Ammeter measures
flow INSIDE
the circuit
V = 100V V
100V

8. PRELIMINARY SUMMARY Name and draw 8 of the circuit elements
How is the voltmeter connected to a circuit?
How is an ammeter connected to a circuit?

9. Two types of Circuits
Series Circuit: When two or more resistors connect end-to-end in series with each other forming a loop.
Parallel Circuit: Current from the power source splits into separate branches such that the resistors are not in series, but parallel.

10. Series Circuit A circuit composed of two or more resistors
connected end-to-end, creating a SINGLE LOOP

11. Series Rules ITotal = I1 = I2 = I3 = …= IN
The equivalent resistance for a series circuit is the SUM of all RESISTANCES in the circuit
RTotal = R1 + R2 + R3 + …+ RN
The total voltage in the circuit is equal to the SUM of the VOLTAGE DROPS across the resistors.
VTotal = V1 +V2 + V3 + …+ VN
The current in the circuit is constant at ALL points in the circuit.
ITotal = I1 = I2 = I3 = …= IN
All COMPONENTS and the WHOLE CIRCUIT obey OHM’S LAW

12. Req = R1 + R2 + R3 = 400Ω 100 Ω 75 Ω 225 Ω R1 R2 R3 10 V I = V / R
I = A
10 V

13. VIR Chart V I R R1 R2 R3 Req 100Ω 75Ω 225Ω 10V 0.025A 400Ω 0.025A 2.5V

14. 50 Ω
120 Ω
150 Ω R1 R2 R3
1.5A
? V

15. VIRP Chart V I R P R1 R2 R3 Req 50Ω 120Ω 150Ω 1.5A 75 V 1.5A 180 V
112.5W
180 V
1.5A
270.0W
225 V
1.5A
337.5W
480 V
320Ω
720W

16. SUMMARY What does a series circuit look like?
In a series circuit, what are the rules for…
Current?
Voltage?
Resistance?