Lesson: Chaper 10 Electrical Resistance

iGCSE Physics Lesson Plan

Learning outcomes for ALL students ("MUST" and "SHOULD"):

*Knowledge of basic circuit symbols

*Concept of resistance and knowledge of Ohm's Law

*Ability to recognise and use fixed and variable resistors - and special ones - LDRs and thermistors

*Ability to measure the resistance and verify Ohm's law

*Knowledge of I-V graphs for resistors, filament bulbs and diodes.

Book References:

Edexcel iGCSE Physics - Brian Arnold

Experiments/Demos:

1. Experiment 1: Ohm's law of resistors: 150ohm resistors, variable voltage power pack, wires, ammeters, voltmeters. 
2. Experiment 2: I-V graph for filament light bulb: as experiment 1 but with a light bulb in the place of the resistor. 
3. Demo 1: LDR, thermistor:  need one of each, a light source, a tub of hot water, a voltmeter. 

Lesson notes: (brief, relevant description of lesson where Class Practicals (CP), Class Demos (CD), Worksheets (WS) etc can be referred to by the initials and the numbers assigned in boxes above)

This may need reworking.  It doesn't really work in this form as double and singles.  Really need to time it so that Ohm's Law with 2 experiments are just the one double.

Lesson 1: (double)

Starter:

1. Who am I? Circuit symbols and their function.  Cut these out and match them up.   

Main:

1.  Stick the "non-resistor" (ahem) components in first (ammeter, voltmeter, light bulb, motor, led, heater, cell, diode).  Make sure that students use the text book to write as much detail on each component - special interest in the diode. 
2. What is resistance? PPT on Ohm's Law (copy) and WS The relationship between V - I and R.
3. Need to practice V = IR. Do WS Electrical resistance Questions 1 - 6, go through each one on the board, remembering LESS is MORE.  Full working. 
4. Stick in "resistor" components: resistor, variable resistor, thermistor, LDR.  Use the text book to write as much as possible about each.  Demo thermistor and LDR.  

Plenary:

1. PPT slide - explaining how to verify Ohm's Law. Do experiment with 150Ω resistors (single and then 2 in series or a 300Ω resistor).  Probably only time to just take the results.  To record use WS How voltage, current and resistance are related.

Suggested homework tasks (differentiated where appropriate):

1. Complete the experimental write up.  Need graph paper and need to consult the book to ensure that they plot the correct variables on each axis.  Leave determining R until next lesson.
2. PREP Current resistance and voltage

Lesson2: (single)

Starter:

1. Look at the graphs.  Determine the gradient and from that the resistances of their experiments. Really focus on taking large triangles for the gradient, full annotation and final units. 

Main:

Take readings for the filament bulb.  Stick in WS Current V voltage for a filament bulb and merely require students to record a neat table and plot the graph.  Again, refer them to the text book where they will see that the graph should tail off at higher values of voltage. Students need to take the gradient for the linear part of their graph. 

Lesson 3: (double)

Starter:

1. Remind students of the difference between Ohmic and Non-Ohmic.   From:  CNS I-V graphs components and functionality.  

Main:

1.  Continue with this worksheet by cutting out the components and matching up with their functionality. 

Plenary:

Suggested homework tasks (differentiated where appropriate):

1. PREP Current Voltage Graphs