1. Equipment Electric Circuit kits Ammeters Volt Meters
See if students can remember the measurement of energy

2. Recap – key words Two Word Tango Two word tango..
Play the music in the link
Students have to put a keyword in the ’gap’
Have boys vs girls, left vs right etc and run best of 3 or 5 rounds.
Any key word from electrical circuits is ok. Repetition or missing the gap is a loss!
Music speeds up as you go along

3. Lesson intentions:
To understand how resistance is added in series.
Date and title: Series Circuits
9 May, 2019
S t e p s
t o
S u c c e s s
Learning outcomes:
Calculate the total resistance of two resistors placed in series.
Find the potential difference across a component in a circuit .
Explain in detail why the current in a series circuit is the same at all points 4 6 12 8
Key words: Series, Parallel, Resistor, Current, Potential Difference

4. Bigger picture Topic Potential difference and resistance
Component characteristics
Current and charge
Series Circuits
Topic
Electrical Circuits
Parallel Circuits

5. Build it Results A1 = A2 = A3 = Results V1 = V2 = V3 = Idea Rtotal =
Using practical equipment please try and work out/prove a rule for current and potential difference for a series circuit.
Using your mind please try and work out how we work out the resistance of a whole circuit if there is more than one resistor in series V1 A1 A3 A2 R1 R2
Quickly run through the basics of builing the circuits.
Students should build the first 2 circuits (They will have to move the ammeter and voltmeters around the circuit as there are not enough to have 3 of each)
Ensure students are clear on how to wire in Ammeters (series) and voiltmeters (parallel)
They must think abot the resistors in series to try and work that out.
When bringing it back together at the end of the practical see if the students can work out the patterns in their results from what they see. V2 V3
Results
A1 =
A2 =
A3 =
Results
V1 =
V2 =
V3 =
Idea
Rtotal =

6. Rules and why
Current is the same throughout a series circuit Potential Difference of the power source in a series circuit is split between the components. Resistance is added up in a series circuit.
…because there are the same number of electrons flowing past a point in one second. In a series circuit there is only one path to take.
….because the energy is split between the components that use it. If the components are identical in resistance if one has a higher resistance it will have a potential difference across it.
….because the current (electrons) have to go through all the components. It is more difficult for the electrons to get through a number of resistors and therefore the total resistance of the circuit is higher.
You can pupil model the current moving around a loop with a few students and how much has to go past each part in the circuit
Ask SDe for help with this model if needed.

7. Series Rules Summary
Current is the SAME everywhere in a series circuit Potential Difference is SHARED across all components. If the components are identical it will be split evenly Resistance is ADDED
You can pupil model the current moving around a loop with a few students and how much has to go past each part in the circuit
Ask SDe for help with this model if needed.

8. Calculating series resistance
Resistors in series cause more resistance to the current.
Total resistance equals
the sum of all resistances.
RT = R1 + R2 + R3 + … Rn
Talk through the use of R1 + R2 + R3 notation.
Link to maths and algebra… in maths they would use A + B + C = D
In science we use the subscript to help iudentify differences.
RT = = 9Ω

9. Bringing it all together!
Don’t Forget the 3 important rules for series circuits!
1) Find the total resistance of the following circuit. R1 R2 R3
RT = R1 + R2 + R3 =
= 24 Ω
2) Find the currents in the ammeters if the current in R3 is 2A.
Practice questions.. Remind them to use the 3 rules of series circuits and that voltage will need to be calculated individually for each component.
Series circuit: I1 = I2 = I3 = 2A
3) Find the voltage on R1 , R2, R3
I1 = 2 A
R1 = 5 Ω V1 = ?
R2 = 10 Ω V2 = ?
R3 = 9 Ω V3 = ?
V1 = I1 x R1 = 2 x 5 = 10V
V2 = I2 x R2 = 2 x 10 = 20V
V3 = I3 x R3 = 2 x 9 = 18V

10. Bringing it all together 2!
From the following circuit, find:
a) the combined resistance
b) the current flowing through R1 and R2
c) the voltage across R1
d) the voltage across R2
R1 = 6 Ω
4 v
R2 = 2 Ω R1 R2
a) RT = R1 + R2 = = 8 Ω
b) IT = VT / RT = 4 / 8 = 0.5 A
Series circuit: IT = I1 = I2 = 0.5 A
c) V1 = I1 x R1 = 0.5 x 6 = 3V
d) V2 = I2 x R2 = 0.5 x 2 = 1V
Check yourself:
VT = V1 + V2 ? 
4 = 3 + 1