Na-8 Band Gap Energy
Published: Friday 17 March 2006 - Updated: Thursday 31 March 2011
To demonstrate the bang gap energy of a pn junction.
- Blue LED
- Red LED
- Desk Lamp
- U.V. source
Click on pictures to enlarge.
A red LED is illuminated with a desk lamp. The photons have enough energy for the electrons to overcome the energy gap in the pn junction and a current is displayed on the galvanometer. If the same desk lamp illuminates a blue LED the photons do not have enough energy to produce a current flow. However if the leds are illuminated with a UV source a current will now flow.