Fact 1: Alight bulb converts electrical energy into light energy when it is turned on.

Fact 2: Aphoton is a packet of light energy.

Given the two facts above, answer the question "A light bulb emits what when turned on?" with the following options: 
- movement
 - warmth
 - photons
 - sunlight
 - motion
 - sun's heat
 - dangerous
 - Heart rate


 

   photons      