1. Circuits Day 3

2. Warm up Clear your desk for the homework quiz. Use your own paper – there is scrap paper on the lab table if you need it. – Note: #2 the question says 5 resistors – but there are only 4 as per the diagram.

3. Circuits Video Hewitt Video (on the USB drive)

4. Equivalent Resistance How many different resistances can you make out of three 5Ω resistors? There are 7 different arrangements and values – The first 3 students to drawn them out and calculate the values get a Husky Ticket.

5. Equivalent Resistance: series & parallel

7. Power Example Determine the power dissipated in the 5 Ω resistor in the circuit shown below Hint: figure out the current or voltage of that resistor to use one of the power equations

8. Resistance in wires Short circuits – steel wool and 9V Superconductors (video later) – http://hyperphysics.phy- astr.gsu.edu/hbase/solids/scond.html http://hyperphysics.phy- astr.gsu.edu/hbase/solids/scond.html

9. Resistance in wires

10. Resistivity What is the resistance of 3.0 m of copper wire with a radius of 1 mm?

11. Resistivity What is the resistance of 100.0 m of copper wire with a radius of 1 mm?

12. Resistivity What is the resistance of 100.0 m of silver wire with a radius of 1 mm?

13. Resistivity Why are houses wired up with copper instead of silver?

14. Superconductors https://www.ted.com/talks/boaz_almog_levit ates_a_superconductor https://www.ted.com/talks/boaz_almog_levit ates_a_superconductor

15. Closing