Chapter 13 - Quantum Physics Flashcards
What is Planck’s Constant
6.63 x 10^-34 m2 kg / s
How to calculate energy
E = hf or E = hc/λ
How to calculate the power
Power = n h f (energy x number of photos passing a point)
What is 1 eV
The work done on an electron in accelerating between a potential difference of 1V.
How to convert between 1eV to J
Divide by 1.6 x 10^-19.
On a V- 1/λ graph, what is the gradient?
hc/e
What is photoelectric emission
The emission of electrons from the surface of a mental, where is it illuminated by EM radiation above the threshold frequency.
If you increase the intensity of the incident radiation, what is affected?
The number of photons emitted per second from the surface of the metal.
If you increase the frequency of the incident radiation, what is affected?
For as long as the frequency is above the threshold frequency, the kinetic energy of the photons will increase.
What is work function
The minimum amount of energy required for an electron to escape the surface of the metal.
On a J- f graph, what is the Gradient equal to
H
On a J- f graph, what is the y intercept equal to
- Q (the work function)
On a J- f graph, what is the x intercept equal to
The Threshold Frequency
Proof for Light being a wave
Diffraction, Refraction and so on.
The Double Slit Experiment.
Proof for Light being a particle
The Photoelectric Emission.
Also the Gold Leaf Electroscope.
Explanation behind light is a particle (packets of energy)
During the Gold Leaf Electroscope experiment, they noticed that it didn’t matter for how long light of a frequency below was given to the plate, the electrons wouldn’t leave the surface of the metal. However, if you increase the frequency, above the threshold, the electrons would leave.
This was evidence that energy is received in packets. It didn’t matter for how long, or how intensely these packets were given, if they didn’t have the required amount of energy, the electrons wouldn’t leave.
But, by increasing the frequency and giving more energy in each packet, then the electrons would leave.
Momentum and wavelength
Wavelength = h / p
Kinetic energy and Wavelength relationship
If kinetic energy decreases by a factor of 2, wavelength will increase by a factor of root 2.
How to calculate the number of electrons
Current divided by 1.6 x 10 ^-19
