Photoelectric Effect Flashcards
What was first used to describe/show it?
Cathode ray tube: the cathode became positively charged when UV light was incident upon it
Results of the photoelectric effect
1) no ___ were emmited until what?
Difference between quantum theory and wave theory
1) electrons—no matter how intense the EMR was until a certain minimum frequency was reached
Intensity/amplitude does not cause photo emission but wave theory says it should. Quantum says E is directly proportional to frequency and it causes photoemission
Photoelectric effect
2) is f is is smaller than do what happens?
No electrons are emitted no matter how intense the EMR is
3) is f is bigger than fo what happens?
Electrons are emitted instantly, no delay at all
-wave energy takes some time to be absorbed
4) each material used as a cathode has its own ___?
Threshold frequency
5) is f is bigger than fo AND the emr is intensified what happens?
More electrons are emitted
-with quantum theory more photos means more e-‘s, and since each electron can absorb a single photon this means photoelectric current increases
(Wave theory says bigger intensity, bigger electron energy but it doesn’t)
Scientist responsible?
Heinrich Hertz
6) is f is bigger than fo AND f is increased what happens?
The emitted electrons have more energy (faster)
Conservation of energy equation for the photoelectric effect
Ephoton=Eke- + W
Variations of the conservation of energy equation
Hf=1/2mv^2 +hfo
Hc/wavelength= qVstop + hc/threshold wavelength