P5.3 Flashcards
What is angle of incidence and angle of reflection?
Angle of incodence is the angle between the ray and thr normal (normal to the boundary its hitting )
Relfection is angle from reflected ray and normal
REMEMBER ITS FROM THE NORMAL AND RAY NOT THE GROUND AND NORMAL
Law of reflection
Angle of incidence is always = to angle of reflection in any surface and wave
If drawing a wavefront diagram what should be remembered about the actual waves (wavefronts)
So draw your angle of incidence and refraction and normal but make sure the wavefronts are perpendicular to the path of the wave (angle of incidence thing)
The wavefronts are peaks from birds eye view
What is a virtual image
An image which appear to diverge from a point
- essentially inside a mirror
Diverge just means spread out
2) a virtual image cant be potjected on to a screen as inage is in the mirror.
How does reflection work in a mirror and so where do the light actually come from?
1) two rays coming out of image into mirror
2) these get angle of incidenced each, but then also extended out beyond in the mirror
3) where they meet is the virtual object
Although it seems that the rays are coming frim the virtual inage they actually coming from the object, which is just getting reflected into your eyes…
What three things can happen when a wave meets a medium
What makes one of these happens
1) transmitted across, the wave isnt changed
- hiwever could become refracted( change direction and speed)
2) energy absorbed so doesnt go through the material
3) reflected
The properties of wave and material involved
What is refraction in a wave
When a wave changes direction from one medium to other
- this happens because wavespeed changes and this means the wavelength will change too as frequency is constant
What causes the amount of energy transmitted absorbed or relfected
The media
Distance wave came frim
Wavelength it had
How do EM waves interact going into dense and out of dense mediums
What bout normal incidence
1) going into dense it slows down meaning wavelength decreases and bends TOWARDS NORMAL
2) going out wavespeed increases and bends away FROM NORMAL as wavelength also increases
When normal incidnece haopens it doesnt refract like that but speed changes. SLOWS DOWN AT ONCE
Now when looking the rays are coming from a different place thus looks like straw is bent
How does wavefronts move from deep to shallow?
Shallow water they live more slower meaning wavelength decrease and bend towards normal
Therefore they becomes more bunched up
What is relationship between wavelength and refaction and how does that make a rainbow
What dispersion
What type of medium specifically need and why
How can you show the differnt wavelengths refact differently in a quick practical?
The smaller the wavelentgh the bigger the refraction. This is because they slow down more so smaller wavelength and bend more to normal
When the white light is spread out
When white light is refacted, its different wavelengths will mean it will refract differently and split. For example red bends the least but violet bends more. Red has higher wavelength so regact less. Different colours have different wavelengths so thats how, they make rainbow
2) a prism, as it doesnt have parallel boundires meaning angle of incidence isnt the same both times and the wavelengths are actually refracted differently
3) ray block with filters that shine only red light, trace incidence refraction and same with blue, should see they refact differently
How does colour work and how do filters work
-how does object behind colour filter look
Different objects absorb and transmit and reflect colours differently. An object that absorbs all frequencies but reflects red will be seen as red.
This is the case for opaque objects, they dint transmit lightbjust absorb and relfect
All light ha sky’s own wavelength, but you can make them to except for red green blue, if you see yellow it relects combination if both
- eg white objects reflect rgb , black absorbs all of them (no light)
2) Colour filters absorb all light and transmit the one you want out, so you see that.
- if a red filter and green filter put next to each other you see black as now together all colours are filtered
- now if you put red hat behind red filter it is red but if blue then black because light reflected off blue is absorbed and lack kf light = black
(If it is say cyan filter will let out cyan and primary colours that make up cyan)
Scattered vs specular reflection
Why in scattered can you not see virtual image
Dark vs light cloud (scattering/ absorb)
Specular is regular reflection such as plane mirror- this is why you see images as virtual
Scattered is when scatter is diffuse. Bumbos or uneven surface means light reflects unevenly. Law of reflection still applies but rays reflect at different angles respectively.Meaning an image cant be formed
However some particles scatter everythint so it seems white and doesnt matter. Or they absorb everything and seems black
How does concvex lens (converging) lens work and how to do ray diagrams
It refracts to a focal point
1) draw image, parallel ray goes ti middle and refracts through the focal point. ( this point in which laralle lines refacted meet up at)
2) diagonal line goes theough that doesnt bend. Where these meet makes a REAL image, inverted however and diminished
What happens when convex lens changes its distance and how can fore happens?
2F and beyond
F to 2f
Less f
Diverge? Virtual
If beyond 2F and 2F
- real, inverted but diminished or the same height here
If F to 2F
- real inverted magnified
If less than F
- VIRTUAL upright magnified, this how magnifying glass works
- goes through focal and middle, rays extened to produce virtual image on left
Remember real image is image which is formed by light rays that seem to have diverged by there.
