1. To begin…
Can you explain this….

3. Resistance What is resistance?
Answer this question …. …..for 3 marks …..for 5 marks …..for 7 marks
Resistance
BY THE END OF THE LESSON: ALL MUST: Recall what is meant by resistance and how it arises. MOST SHOULD: Derive the resistor rules for series and parallel. SOME COULD: Make links between these quantities and use homogeneity to verify these links.

4. Conductance and Resistance
Chapter 3: Sensing
Conductance and Resistance

5. Learning Objectives
To be able to effectively carry out a series of measurements to demonstrate you meet the CPAC criteria.
To be able to describe and explain how resistances add up in parallel and series.
To be able to describe the relationship between resistance and conductance and to know the unit Siemens.
Friday, 05 April 2019 6

6. Learning Outcomes ALL MUST:
Recall what is meant by resistance and how it arises.
MOST SHOULD:
Derive the resistor rules for series and parallel.
SOME COULD:
Make links between these quantities and use homogeneity to verify these links.
Grade E
Grade C
Grade A
Friday, 05 April 2019 7

7. Investigating resistance and length
Boardworks GCSE Additional Science: Physics
Resistance and Resistors
Investigating resistance and length
Teacher notes
This simulation activity could be used to investigate the affect of the length of a coil on resistance. It could be used a precursor to running the practical in the lab, or as a revision exercise. To extend the activity, students could be asked to calculate the resistance in ohms in their books before revealing the resistance on the IWB.
BY THE END OF THE LESSON: ALL MUST: Recall what is meant by resistance and how it arises. MOST SHOULD: Derive the resistor rules for series and parallel. SOME COULD: Make links between these quantities and use homogeneity to verify these links.

8. How is resistance affected in a series circuit?
Boardworks GCSE Additional Science: Physics
Resistance and Resistors
How is resistance affected in a series circuit?
4 
2 
When two (or more) resistors are connected in series, the combined resistance is higher than the individual resistors.
Q: Attempt to prove this using ideas about pd and current in a series circuit.
total resistance in series, RT = R1 + R2+………Rn
BY THE END OF THE LESSON: ALL MUST: Recall what is meant by resistance and how it arises. MOST SHOULD: Derive the resistor rules for series and parallel. SOME COULD: Make links between these quantities and use homogeneity to verify these links.

9. Investigating resistance and thickness
Boardworks GCSE Additional Science: Physics
Resistance and Resistors
Investigating resistance and thickness
Teacher notes
This simulation activity could be used to investigate the affect of the thickness of a coil on resistance. It could be used a precursor to running the practical in the lab, or as a revision exercise. To extend the activity, students could be asked to calculate the resistance in ohms in their books before revealing the resistance on the IWB.

10. Why does thickness affect resistance?
Boardworks GCSE Additional Science: Physics
Resistance and Resistors
Why does thickness affect resistance?
Increasing the thickness of a wire increases the surface area that the electrons can flow through.
This decreases the chance of collisions with metal ions.
In thick materials the charge carrying particles are able to move through the conductor more easily, reducing resistance.
BY THE END OF THE LESSON: ALL MUST: Recall what is meant by resistance and how it arises. MOST SHOULD: Derive the resistor rules for series and parallel. SOME COULD: Make links between these quantities and use homogeneity to verify these links.

11. How is resistance affected in a parallel circuit?
Boardworks GCSE Additional Science: Physics
Resistance and Resistors
How is resistance affected in a parallel circuit?
2 
4 
The total combined resistance is less than any of the individual resistors.
Q: Attempt to prove this using ideas about pd and current in a series circuit.
Total resistance
= R1 x R2
R1 + R2 1
total resistance in parallel R1 R2 = +
= 4 x 2
4 + 2
EXT: There is a shortcut if there are only two…..
Can you figure out what it is???
= 1.33

12. Conductance in series and parallel…
So, given what you have seen with resistors, what happens with conductance?
BY THE END OF THE LESSON: ALL MUST: Recall what is meant by resistance and how it arises. MOST SHOULD: Derive the resistor rules for series and parallel. SOME COULD: Make links between these quantities and use homogeneity to verify these links.

13. Look at this circuit…
Find the current drawn from the supply and the p.d across the 4 ohm resistor.
BY THE END OF THE LESSON: ALL MUST: Recall what is meant by resistance and how it arises. MOST SHOULD: Derive the resistor rules for series and parallel. SOME COULD: Make links between these quantities and use homogeneity to verify these links.

18. Boardworks GCSE Additional Science: Physics Resistance and Resistors
Resistors in a circuit
Teacher notes
This calculations activity could be used as a plenary exercise to check students’ ability to calculate the total resistance when resistors are placed in series or in parallel.

19. Homework Task 4 in booklet
Challenge Q as extension for those that are capable.
BY THE END OF THE LESSON: ALL MUST: Recall what is meant by resistance and how it arises. MOST SHOULD: Derive the resistor rules for series and parallel. SOME COULD: Make links between these quantities and use homogeneity to verify these links.