Unit 1 Flashcards
What does coherent mean in terms of waves?
Constant phase difference
What is produced when there is a bright fringe?
Maxima, in-phase, constructive interference
What is produced at dark fringes?
Minimum, out-of-phase, destructive interference
If wavelength is decreased what happens to the maxima separation?
Decreases
What colour of light diffracts the furthest?
Red, longer wavelengths
What is the test for wave behaviour?
Causing an interference pattern
Explain Young’s double split experiment?
- splits one source of light into two
- produces coherent light waves
- interference pattern
What happens when white light passes through a diffraction grating?
Central order maximum is white, remaining maxima are spectra
Why does white light produce a white central order maxima?
All wavelength meet in-phase, constructive interference
What effect does increasing the slit separation have on the interference pattern?
Decreases fringe separation
What is refraction?
When light changes speed as it passes from one material to another
What is absolute refractive index?
The ratio of the speed of the incident ray in a vacuum to the speed of the refracted light in the material
Angle theta (01) is always the angle in what?
Air
Will a longer wavelength diffract more or less?
Less diffraction
What is the critical angle?
Angle of incidence that causes light to refract at 90 to the surface
When does total internal reflection occur?
If the angle of incidence is increased above the critical angle
What is irradiance?
The power per unit area
What is a point source?
Source of light that appears to have no dimensions to the observer
When does the irradiance of a point source decrease?
As the distance increases
When is a spectrum produced?
By photons of light being emitted, as electrons make downwards transitions between energy levels within an atom
Does an upward transition absorb or emit energy?
Absorbs
When will an electron make a transition?
If the energy of the absorbed photon equals the amount of energy needed to move between levels
Which level is the excited state?
E1
Will a smaller drop on the emission spectrum produce a shorter or longer wavelength?
Longer
What is all matter made of?
Fermions
Name the two types of fermions?
Quarks, leptons
What are hadrons made of?
Quarks
Name the two types of hadrons
Baryon and messon
Name the force carrying particle
Boson
What is antimatter?
Identical to matter except they have opposite charge
What is annihilation?
When matter and antimatter meet they annihilate each other, leaving behind energy
What was discovered during beta decay?
Electron neutrino
What acts on masses?
Gravity
What does electromagnetism act on?
Charges
What type of force acts during beta decay?
Weak nuclear force
What force acts between quarks?
Strong nuclear force
What is conserved during particle interactions?
Charge
What is an electric field?
The region where a charge will experience a force
Why do charges accelerate in an electric field?
Due to an unbalanced force
What way do the arrows point on a positive charge?
Point away
What way do the arrows point on a negative charge?
Points towards point
What does a potential difference of 2.5kV mean?
2500J needed to move 1 coloumb of charge across electric field from one plate to another
What are the 3 types of particle accelerators?
Linear accelerator, cyclotron, synchrotron
What does a particle accelerator do?
Causes particles to collide with each other
Why are particle accelerators important?
At high energies can recreate conditions at Big Bang and investigate the particles that existed
What is a magnetic field?
A region that can exert a force on a charge
What kind of charge creates an electric field?
Stationary charge
What kind of field does a moving charge create?
Magnetic field
When using the right hand rule what does the middle finger represent?
Negative charge or current
What symbol is used to represent the field lines pointing into page?
X
What is a (.) used to represent in terms of field lines?
Field lines point out of page
What is a nuclide?
Nucleus with a specific number of protons and neutrons
Define an isotope
Nuclides with the same atomic number but different mass number
When a radionuclide decays what does it emit?
Radiation or particles to become a more stable daughter product
What type of nuclear fission occurs naturally?
Spontaneous nuclear fission
How does induced nuclear fission occur?
Large nucleus is bombarded with a neutron which splits the nucleus into smaller nuclei with the realise of energy and neutrons
How does an induced nuclear fission reaction release energy?
The total mass before is greater than the total mass after. The loss in mass is converted into energy using E=mc^2
During nuclear fission what is conserved?
Atomic and mass number
What is nuclear fusion?
When two smaller nuclei join to make a larger nucleus
What are quanta of energy?
Fixed or discrete amount of energy, directly proportional to frequency
What are photons?
Quanta of energy
What is the photoelectric effect?
Photon energy is absorbed by the electron and becomes a free electron
What type of emission is best for the photoelectric effect?
A UV photon
What type of charges need to be present in the metal for the photoelectric effect to work?
Negative charges
What does the metallic surface need to have for photoelectric emission?
Low enough work function/ threshold frequency
What quarks make up a baryon?
3 quarks or 3 anti-quarks
What quarks make up a messon?
1 quark and 1 anti-quark
Give an example of a meson
Pion
What happens to the photoelectric current as photon energy increases
Photoelectric current increases
Define work function
Minimum amount of energy needed to bring an electron to the surface of the metal
Define threshold frequency
Minimum frequency an incident photon needed to bring an electron the surface of the metal
