Question

The electric eye that prevents an elevator door from closing when you are in the doorway relies upon which physics principle?
More than one may apply to this question
-special relativity
-atomic spectra
-photoelectric effect
-radioactivity

Answer 1

It's Photoelectric Effect, I just a test with this same question. I am not good for explaining exactly how, but I was right.

Answer 2

Just took the test as well that dude is right.. lol I rested my grade in your hands and I got an A.. for more help with that test all answers on here are 100% correct: https://quizlet.com/212791759/1007-unit-10-test-part-1-flash-cards/