Light + Wave Flashcards
what type of wave is light and what type of wave is sound
light = electromagnetic sound = longitudinal - requires medium
does light require a medium to travel
no therefore it can travel in a vacuum
refractive index of air
1
refractive index of water
1.3
what happens when changing mediums
velocity changes but frequency doesn’t
wavelength of red light
700nm or 750??
wavelength of violet light
400nm
electromagnetic spectrum from lowest energy highest wavelength to hight energy shortest wavelength
radio wave microwave infrared visible ultraviolet xray gamma ray
what is the wave particle duality
light travels as a wave but interacts like a particle
two equations from the energy of a photon
E = hf E = hc/wavelength
what is diffraction
how a waves bends when it encounters an obstacle
a smaller gap for a wave to go through will result in a _____ diffraction
wider
what is constructive interferance
waves will add when path length is a multiple of the wavelength
what is destructive interference
waves cancel
what is the angle of reflection in relation to the angle of incidence
angle of incidence = angle of reflection
**in reference to the normal perpendicular to the surface
equation for refraction index
n = c/v
why is n always >1
because light is fastest in a vacuum
what happens to velocity as n increase
slows down
what is dispersion
splitting of white light by a prism
how does light disperse through a prism
violet (higher n and faster) bends more
red (slower lower n) bends less
what is the cause of refraction
when going to different mediums of differing n the velocity of light changes causing a bend
how will light bend going from low n air to high n water
towards the normal
what is snells law what relationships can we get out of this
n1sin1 = n2sin2
if we are going to a higher n than the angle will have to be smaller
what happens if light enters the air the water at an angle of 0
keeps going straight bc sin0 = 0 refraction
what are the 2 requirements for total internal reflection
going from a high n to a low n (water to air)
large angle of incidence
what happens to the angle of refraction when the critical angle is reached
it is 90 degrees
what is the critical angle
angle of incidence when the angle of refraction is 90 so total internal reflection occurs
** be aware of questions if they are asking for the refraction or incidence angle
what do you need to know about what electromagnetic means
light has both electric and magnetic components which are perpendicular to each other and perpendicular to velocity of the wave
think of x y and z fields
what is polarization
light is naturally in all different directions from each other
when it goes through a polarizer it only lets light waves of a certain orientation through
resulting in a uniform orientated light beam
polarized sun glasses prevent glare
what is circular polarized light
direction of the fields rotate steadily over time either clockwise or counterclockwise
if something has high absorbance at 700nm what color would it be
not red because color is what is reflected
relate to space about the difference between sound and light
light can travel through a vacuum which is why we can see
sound can’t travel through a vacuum which is why you can’t hear anything in space
what is c
EM velocity in a vacuum
speed of radio waves or light waves in a vacuum
3x10^8
master wave equation
v = wavelength x frequency
value of planks constant
6.64x10^-34 m^2kg/s
what property of waves correlates with its energy
frequency!!
if light travels from n = 2 to n =2 will there be a bend or refraction
no because no change in velocity
to find the nth max in single vs double slit defraction which length is used
single slit is the length of the aperture
double is the distance between 2 aperture
what is color of light dependent on
frequency
