1. Be able to describe how the resistance of a diode varies.
11 November 2018
Diodes I
Objectives
Be able to describe how the resistance of a diode varies.
HSW: AF4 – Using investigative approaches
Used before in: lesson 6 - lamps
Will use again in: lesson 8 – Non-Ohmic devices
PLTS: Team workers – Work collaboratively with others.
Will use again in: lesson 78 -Non-Ohmic devices
Keywords
Current (I), Amp, Voltage (V), Volts, ammeter, voltmeter, resistor, diode, LED, resistance (R), Ohm.
Fascinating Light Emitting Diode (LED) Facts!!
An incandescent light bulb gives off only 10 percent of its energy as light, the rest is heat. Almost 100 percent of an LED's energy is given off as light.
Replacing half of all Christmas bulbs with LED bulbs would cut U.S. energy bills by $17 billion annually.
Kentucky recently switched 77,000 traffic signal modules from incandescent lamps to LEDs. The state estimates it will save $1.7 million from reduced energy costs and $1.5 million in reduced maintenance and lifecycle costs.

2. OUTCOMES
All students should be able to describe that not all components conduct electricity by Ohm’s Law.
Most students should be able to test circuits for current and potential difference and describe that the resistance of a diode varies as the potential difference varies.
Some students should be able to recall the shape of the graph and relate it to the resistance of a diode as the potential difference varies across it.

3. How does an LED work?

4. Current-Potential Graph of a filament bulb
Set up the equipment as shown:
Vary the PD and take readings of current.
Analysis
Once you have a set of results draw a graph of Current on the y-axis and PD on the x-axis and write a conclusion.
Results
Potential Difference, V (V)
Current, I (A)

6. Electrical Hotseat
Your teacher will choose 1 person to be on the hotseat.
Can you come up with questions from this or previous topics that will challenge them?