Quantum Flashcards
What does Quantum physics explore?
EM radiation and subatomic particles like electrons.
Who founded Photons and what are they?
Planck discovered EM is quantised
A ‘packet’ or ‘quantum’ of EM radiation.
What does the photon and wave model show?
Photon model - how EMR interacts with matter
Wave model - propagation of waves thro space
What is directly proportional to frequency?
Energy of photon
E = hf
What equations get E = hc/landa
E =hf
c =flanda
What is an electronvolt
1ev is the energy transferred to or from an electron when it moves thro a pd of 1V
How to go from Joules to Ev
Divide by 1.6*10^-19
How is eV related to J?
From W = VQ = Ve
1 * e = value
Explain all points of determining planck constant frm LEDS
- Led only emit at threshold pd
- Potential divide, vary, record, repeat, mean, uncertianity
- Graph V against 1/landa
- m = hc/e
- Calculate h
What is the definition of phototelectric effect?
The emission of electrons from the surface of a metal when EM waves with frequency greater than threshold f, are incident on the metal.
Give a real life example of Photoelectric effect?
Spacecrafts, interfer with electric components
Explain the gold leaf electroscope.
- Zinc plate ontop of negatively charged rod and gold leaf (attached)
- UV light cause effect, leaf retract to centre rod
What observations can be made from gold leaf electroscope?
Visible light does not work as photon energy less than work function. intensity dont matter as one to on interaction
UV has required energy, intensity increase rate
Photon energy come frm threshold frequency
Why does some photoelectric travel faster?
some electrons need more energy as position to positive ions. More enery for this, less energy for kinetic
What was the gold leaf electroscope origionally used for?
measure pd.
How do night vision goggles work?
Image intesnifier used effect, metal often semiconductor, suitable work function.
Where did Einstiens effect equation come from?
Applied conservation of energy to all.
what does f0 mean? What does this mean for equation?
Threshold frequency, zero kinetic enery
hf = @ + KEmax (0)
Explain graph used for this Einstiens equation.
Kinetic energy against frequency.
M = h
M same no matter material.
Do photons have a charge?
No
Do photons travel at the same speed in a vacuum?
Yes
Is watts a unit of energy?
No
