physics Flashcards
equation for force and energy in a spring
F = kx E = 1/2 kx^2 = 1/2 Fx
what is a coherent wave?
waves that have the same frequency and maintain constant phase relationship/ have the same wavelength
when waves a and b are on a displacement/ distance graph, which one is ahead?
the one that is shifted to the left
when asked about phase relationship of two waves, what are the two things you need to include?
which one is ahead/ behind and by how much
what two things do you need from both sources to see a clear interference?
coherent waves and similar amplitudes
what equation links wavespeed, tension and mass per length?
v = √T/μ
what is the equation for intensity?
I = power / area
what is refraction?
when a wave changes speed, direction and hence wavelength as it passes into a different medium. (frequency stays constant)
which way does light bend when travelling through a medium?
low to high n: bends towards normal
high to low n: bends away from normal
how does light change with different angles of incidence?
i < r: refraction
i > r: TIR
i = r: 90 degree refraction
what is the difference between spectra and the photoelectric effect?
the photoelectric effect removes electrons from the surface of a metal with UV light.
spectra excites electrons but they are not emitted
what is the dE bRoCcOLi hypothesis?
all waves have a wave and particle nature and λ = h/p
what do you need to change to make an ultrasound more detailed?
decrease wavelength or increase frequency to do so.
how do you change electron volts to joules and vice versa?
q is 1.6*10^-19, electron volts is v and joules is E.
E = vq
or v = E/q
what is an energy band?
a discrete energy level electrons are allowed to exist at within an atom.
how is the emission and absorption spectra used?
emission spectra shows light given off deexcited electrons is diffracted and split up into the discrete wavelengths its made of. (electrons exciting hot gas)
absorption spectra diffracts light that has travelled through a gas to show the missing wavelengths. (light shone through cold gas)
what is Snell’s Law?
n1 sinθ1 = n2 sinθ2
what is the refractive index for air?
1
what are converging and diverging lenses?
they make parallel waves meet / move apart
what is d and n in nλ = d sinθ?
d: 1 / lines per mm (distance between lines)
n: order of diffraction
why does velocity change diffraction angle?
λ = h/p so increasing v decreases λ
less λ means less θ because nλ = d sinθ
how do you know what type of lens is producing a virtual image?
if the object is between the focal length and the lens, its a converging lens. otherwise a diverging lens
what does the IV graph of a diode look like?
curves up from following the x axis at a positive x value
what does the IV graph of a filament bulb look like?
S shape through the origin