Ch19 Continue Flashcards
Chandrasekah limit
The maximum mass of a white dwarf. It is 1.4 solar mass.
Energy levels in atom
Rules:
- An electron cannot have a quantity of energy between the energy levels.
- energy levels are negative because external energy is required for an electron to escape.
- the lowest level is known as the ground level
Electrons/photons in energy levels
- If an electron goes down an energy level, a photon is emitted.
- if an electron jumps an energy level, a photon has been absorbed.
- change in energy = Ephoton
Types of Spectra
Emission line spectrum:
- when we heat a gas, the gas produces light, if u take the light and pass it through a diffraction grating or prism, a spectrum is formed, the spectrum is made up of certain discrete lines, indicating the presence of only certain wavelengths.
Absorption line spectrum:
- when light passes through heated gas, it produces black lines in its spectrum, the absorption lines show that certain wavelengths have been absorbed.
Continues spectrum: if we split up white light using a prism, the colours will blend together, leaving no gaps in the spectrum, this shows that white light have a continuous spectrum.
Diffraction gratings experiment
Experiment to determine the wavelength of light:
Measurement:
- with a ruler measure the distance from the diffraction grating to the screen D
- measure the distance from the central maximum to the individual fringes (x1,x2, etc)
- take measurements multiple times and average to improve accuracy.
Analysis:
- calculate the angle using tan^-1(x/D)
- calculate d using 1/N where N is the number of lines per m.
- plot a graph of n against sin&, the graph should be straight line through the origin with gradient of d/wavelength.
Using the equation dsin&=n*wavelength
Weins law
The black body radiation curve will peak at different wavelengths that are inversely proportional to the temperature.
λmaxT=constant
λmax1T1= λmax2T2
Stefans law
L = 4πr^2σT^4
