Objective:
-To demonstrate basic properties of LEDs and the unexpected electrical properties of certain objects.
Apparatus:
- Play-Doh
- a 9V battery
- LEDs
Method:
Roll the Play-doh into “wires” and connect one wire to each terminal of the 9V battery. Connect the LED forward biased and it will light up. Reverse the polarity of the LED and it will not light up.
Notes:
- A 9V battery is necessary for the demo. 1.5V batteries will not have enough voltage to light the LEDs.
- The Play-doh has fairly high resistance (~200 to 300 Ohms per cm for a 1 cm² cross section), which means we don’t have to worry about burning out the LEDs when connected to the Play-Doh wires.
- Try to remove all Play-Doh from the battery terminals and the leads on the LEDs since the salt will corrode the terminals/leads.