If something in a traffic signal converts electrical energy into light energy when it is turned on, then what converts electrical energy into light energy when it is turned on?

Answer choices:
- Something found in a traffic signal
 - deoxyribonucleic acid
 - Something found in a hand mixer
 - Something found in a power strip
 - Something found in a hair dryer
 - polymers of nucleotides
 - a hemisphere is tilted away from the sun
 - an electron microscope

 

 Something found in a traffic signal         