New Flashcards
Why relativistic effects are ignored when (v/c) is less than 0.1
Lorentz factor is approximately equal to 1
Negligible change in length/time/mass observed
What is meant by big bang theory
Universe initially in a hot / very dense state and then expanded
Explain what is meant by length contraction
Decrease in length (In the direction of motion) of an object moving relative to an observer
Reading on Newton Balance
F= Total Mass X A A= f/m Opposite side of force F= MA F= Answer
Explain what is the resultant force
Single force which has the same effect as all the others
Why might an object move upwards
Vertical component of force exerted by eg parachute is greater than weight down
What does a particle accelerator use to accelerate?
Deflect?
Electric fields to accelerate
Magnetic fields to deflect
Changing the irradiance has no effect on frequency because
Max velocity is the same
One photon releases one electron
Each photon has same energy as before
Determining whether constructive or destructive interference has occurred
Path difference
Number of wavelengths = Path difference/wavelength
Constructive for whole number/Destructive for half
Larger refractive index means
Larger change in speed
Possible changes to an experiment
Changing an independent variable eg
Length, thickness, material, colour/wavelength of light
Graph of force/time for softer ball
Will have smaller force over a longer time
Graph of force/time for softer ball
Will have smaller force over a longer time
Why do dark lines occur in the Suns upper/outer atmosphere?
Photons of certain frequency are absorbed in the Suns upper/outer atmosphere
Why do lines appear differently on different spectra?
Light is redshifted/shifted towards red end as galaxies are moving away (from eg sun)
How can varying line emission spectra show expanding universe?
Redshift is greater for distant galaxy meaning it is moving away faster than the nearby one
Comparing 10^-25 with 10^-27
10^-25 is two orders of magnitude greater
Why is mass after a decay less than before the decay
Some mass is converted into energy
What particle physicists suggest to make up for lost energy in a decay
An extra particle, the anti neutrino would have some kinetic energy
Explain how an LED works
When a current passes through a P-n junction photons are emitted
How to carry out experiment differently next time
Set variable eg speed differently and repeat for different speeds
Finding the number of electrons passing between a plate in one minute
Q=IT where T is 60 secs
Number = Q/Charge on one electron
Establishing relationship between irradiance and distance
K= I X D^2
Why is a spectrum of light produced when a white light Ray is used
Each colour/frequency has a different refractive index and therefore the angle in air is different for each colour
Every antiparticle
Has a corresponding elementary particle
The same mass as its equivalent particle
An increase in irradiance will
Maintain kinetic energy
Increase number of photo electrons emitted each second
Distance is greater in frame of reference of
Time is greater in frame of reference of
Earth observer for both
Why spectrum lines are redshifted for a distant star/galaxy
The star is moving away from Earth
Light from the star is experiencing a Doppler shift
Why there is an increase in length between tubes on a linear accelerator?
As proton speed increases they travel further each time
The prism and grating
Produces a spectrum by refraction, grating produces a spectrum by interference
Prism produces a single spectrum
Grating produces more than one spectrum
