Mr. Fleming

 D. 5 Explain how electricity is used to produce heat and light in incandescent bulbs and heating elements.

 Light= Excitation of Electrons

Ground State

Excited State

Ground State

 Light= Excitation of Electrons ◦ Light Bulbs in Microwave Light Bulbs in Microwave ◦ Atoms in Tungsten filament are excited by electricity  Abnormally high melting point ◦ Measure of power in light bulb is Watt ◦ Most energy given off as heat  Only 10% goes to light

 Contains argon and mercury instead of tungsten.  Electricity excites gas molecules in light bulb  Most energy is converted into visible light instead of heat.  Mercury is highly toxic chemical

Ideal for replacement of incandescent lamps Saves up to 75% on energy use Lasts 7-10 times longer than an incandescent Low thermal energy output

▪Can use up to 50% less energy than a CFL. ▪Widespread use over the next 20 years could reduce lighting energy demand by 33%. ▪Currently more expensive to purchase compared to incandescent and CFLs. The NEED Project

 How LED works How LED works  Present in many electronics  Do not have filament  Most energy efficient

The NEED Project

 What is excited to produce light in a CFL? Argon & Mercury Vapor  What is excited to produced light in an incandescent light bulb? Tungsten Filament

 What is the most energy efficient light bulb? LEDs  Name one disadvantage with using this light bulb?