Waves Flashcards
What are some applications of refraction?
Catseyes, Endoscope, Submarine periscopes, Optical fibres, Bike reflector etc.
What two types of lenses are there?
Convex and Concave
What happens when the angle of incident is smaller than the critical angle?
The angle refracts
What happens when the angle of incident is equal to the critical angle?
There is bother refraction and reflection
What happens the angle of incident is larger than the critical angle?
There is only reflection
What is a trait of the amplitude along a progressive wave?
It stays the same along every part of the wave
What is a trait of the amplitude on a stationary/standing wave?
The amplitude varies
What is a node?
A point along a stationary wave with zero amplitude
What is an antinode?
The point of maximum displacement from the equilibrium in a stationary wave
What is absolute refractive index?
When light is traveling from a vacuum’s into glass
How do you find the critical angle?
SinC=1/n then inverse sin
What can be said about the refractive index moving from one medium to the other?
The index moving from denser medium to a less dense medium will have an index smaller than one
How are phase differences represented?
Using radians
What are phase differences used for?
To find superpositions
What is the frequency of the 1st harmonic/fundamental frequency?
F=V/2L , where 2L can also be Lambda
How does an open pipe affect the harmonics?
Both ends have antinodes, but it doesn’t affect the harmonics
How does a closed pipe affect the harmonics?
The closed end has a node and the open end has an antinode causing the first harmonic to equal F=V/4L
What is a photon?
Quantum of energy
What is the model answer for spectrum?
- Ground state electron
- Photon absorbed causing movement to the cited state, which is unstable
- De-excites with emission of a photon
- frequency of the photon determines the wave type
What is the definition of an Electronvolt?
The energy gained by an electron as it passes a potential difference
How much energy is one Electronvolt?
1eV=1.6x10^-19
What is the work function?
The minimum engird required to release a photoelectron
What is the model answer for the photoelectric effect?
- An electron is emitted from a photosensitive material on the basis of two factors
- The photon must be above the threshold frequency
- The photon must has the work function
- Once these were reached the number of photoelectrons released depends upon the intensity of the light
- 1 photon = 1 photoelectron
What can be used to show the photoelectric effect?
The gold leaf experiment
What happens in the gold leaf experiment?
- There is a piece of gold leaf attached to a piece of metal within a vacuum, (a gold leaf electroscope)
- A charged rod is then place on top of the Zinc plate on top of the electroscope
- This charged rod causes a negative charge that then repels the piece of gold leaf from the zinc plating
- When red light was shone on the plate nothing happened
- when small amounts of UV light was shone on the plate, the leaf deceased in angle
- This showed that the repulsion between metals was reducing and hence the charge
