Polarisation of Waves - A Level Physics
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- Опубліковано 8 вер 2024
- In the video I explain the polarisation of waves (including the polarisation of light) for A Level Physics.
Only transverse waves can be polarised, this video explains why. It also shows why sunglasses are known as 'polaroids' and how you can test this yourself on a sunny day.
Update - Please note that the reflected light waves from water are actually horizontally polarised:
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Thanks for watching,
Lewis
This video is recommended for anyone studying A Level Physics in the following exam boards:
AQA
CIE
Edexcel
Edexcel IAL
Eduqas
IB
OCR A
OCR B
WJEC
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Best physics channel on UA-cam, can't thank you enough
+crog ting Thanks - can I quote that on my website?
+A Level Physics Online - Year 13 yeah mate go for it
Thanks. Good luck in your exams.
What is meant by A level physics?
@@ALevelPhysicsOnlineYear13 pp
omg small sneak peek of what physicsonline looks like i love ur vids btw best physics channel
thanks so much for this video :D i'm doing classes from home (corona) and it's really clear and useful
man it's been 3 years since corona, time really flies,
I think that light reflected from the water surface is plane polarised in horizontal plane(not in the plane as you drew) .
When you use sunglasses it only allows light in vertical plane blocking glare ( that is horizontally polarised when reflected. Typical question of this type appeared in June 2011 G482.
You're right. Thanks.
very detailed, clear explanation. An improvement would be to do a worked example as well .Thanks
4:29 the polarized reflected light should be drawn as dots, since the direction of the field oscillation is in & out of the drawing plane.
+HAMDANI YUSUF (dani)
Good observation thanks for that.
After a year of looking for a good physics UA-cam channel, finally found it.
Glad i got to know about tjis channel even though i've only got one month for my AL's here in Sri Lanka!!!! Thank You Sir!!! Your awesome!!
Another nice video, thanks. At 4:37 you combine two phenomena by saying the reflected light is polarised and creates a glare. But I don't understand what one has to do with the other - since polarisation REMOVES light from a source, why should the polarised light cause more glare than otherwise would be the case?
fantastic explanation thank you very much. Had my book in front of me and all the diagrams made more sense the further I got into the video.
i have an exam on Tuesday. thank you very much!
5:24 face 😅😅 anyway thnxx sir ur video fits enough to remember p6 👌👌
This guy needs more subs
Your channel has helped me SO much. Fast, to the point, EASY explanations. KEEP UP THE GREAT WORK!
At Brewster's angle, the reflected and refracted rays are mutually perpendicular
Nice way of teaching. Now only i understand this
great video but please make it a bit darker. Its too bright and it hurts my eyes, maybe put a polarized filter on the camera, ;P
adnan solanki Lower your screen brightness.
+William Preston pretty sure that was sarcasm
+William Preston pretty sure that was sarcasm
Haha probably, I am not sure if the original comment had the pun on the end of it when I replied though. Either way, I might've been sarcastic at the time as well, I can't remember since it was over a year ago :')
why would you reply after a year
one thing, when you polarize light. the rays that go through are perpendicular to the filter. so lets say the opening in the filter was vertical. only horizantal light would go through. its hard to draw tho
That was so cool! Thank you for this!
Its hard to study this but made it easy with illustration
the card models were really helpful
Thank you for the help
Keep going guy, you are great!!
How come when you put sellotape over the filter, light can pass through it even when the second filter is perpendicular? Whats the reason to this?
Molki Bolki I think it's because light still reflects off of the object in between the filters so it will have light with an electric vector in all directions hence thee electric field that's perpendicular would pass through the second filter
Think it's because the sellotape acts as a third polariser.
So the first polariser only allows the vertical component of the lights oscillations to pass through. Polariser 3 (the sellotape) would only let a component of the vertically polarised light through as its axis of transmission is not perpendicular to that of polariser 1.
Then the plane of oscillations of the light reaching polariser 2 is not perpendicular to the axis of transmission of polariser 2 and so a component of this light will pass through.
THANKS FOR HELPING ME....
just wow
Hmm that’s really fascinating. Thank you for this.
Great, nice learning from you.
many thanks.
Concept clear 👍🏻🔥
can't thank you enough
only 270 likes this video deserves more....
Thank u soo much. Very helpful🙏😊👌
Please can you explain the selotape bit at the end?
Thanks!! This helped alot!💖
awesome! explanation
Never seen such diagram in 2d
AWESOME
nice shades bro
Thank you
I think the reflected light is partly polarized not plane polarized ?in 4:30
According to the video, a polariser that is vertically orientated it only lets through the vertically polarised light. So are we saying that is doesn't let through the light that is at 5 degrees off the vertical? 0.0001 degrees off? If this was true then only a tiny fraction, perhaps an infinitesimally small fraction, of the light would be let through. So what part is actually let through? Common sense suggests that light up to 45 degrees either side of the polariser's angle would be let through.
Thankyou!
Thanks
amazing😯😯
Love the accent
1:55
How does that block it all????? There is still a tiny line that made it through
Polarising filters completely absorb light that oscillates 90° to the orientation of the filter. So if you have two filters that are orientated 90° to one another, all light will be absorbed. Light cannot exist as a single line because it needs to oscillate in order to be a wave - a straight line isn’t a wave
@@jacobb7379 🙏
@@jacobb7379 das bs because longitudinal waves and sound waves are only straight lines
@@uknown.p1297 yes but they don’t have polarisation because the oscillate in the same direction to propagation. So longitudinal waves don’t apply to this
how could oscillations not be perpendicular? at any angle would it not still be perpendicular to energy transfer? what does a non-perpendicullar oscillation look like?
Can the opposed be done to only see polarized light?
What is meant by A level physics?
Advance level it is a exam in UK
what do you mean by the analyzer? , is it just the second polarising filter
ZAVELLI 1800 yep, that's all it is.
do you get questioned on malus's law. What type of questions would they be ? are they calculation wuestions
ZAVELLI 1800 You would for OCR spec A, but not for AQA.
cool
Do you need to know the polarisation equations at 3:21 for ocr physics a
i have a doubt which i googled, but even didn't get any answer. my doubt is, " when light passes through a polaroid, electric field components of light in one direction is absorbed . what happens to the corresponding magntic field ?, as light is combination of electric and magnetic field. i mean will the magnetic component in one direction also get absorbed or not?". Can you please clear my doubt?
please explain this statement 'oscillation of polarized is in a single plane which includes direction of energy transfer but direction of oscillation is perpendicular to direction of energy transfer '
ahamed akmal It means that the "motion" of the wave is is directly right angles to the motion of energy (which is just a straight line basically.)
yes i get that part , but 'oscillation is in a single plane which includes direction of energy transfer' what does this mean
ahamed akmal you could easily draw it on a piece of paper as though it was two dimensional. Basically, all of these are travelling on a singular plane, no matter which wave passes through the polariser.
5:26 how does it work, edexcel asks
Why sky light is polarised?
Why wouldn't you explain that a vertical filter allows the vertical component of ALL the angles of polarisation to go through and similarly the horizontal filter, the horizontal components? You describe it as if every angle of field except the light in plane with the polariser are just absorbed so students will expect a tiny fraction to go through a single filter. In fact 50% goes through
From where u get Polaroid
What is the meaning of plane polarisation?
asif alam joy allowing the light to only oscillatie in one direction
Stupid question but why can't longitudinal waves be polarised ?
some person they are already plane limited to the direction of energy travel (parallel)
@@sea5205 so they always move horizontally?
Can someone please tell me a simple definition of polarisation ?
A wave phenomenon in which the wave moves perpendicular to the plane in the direction of the wave motion
Malus' law isn't required on AQA (It is on OCR), so no point learning it if you're an AQA lad
Does anyone know what pens he uses?
you like those pens?
I dont get it
People DO NOT think that the EM waves goes through the gaps in polarising filters... Unless you are told that "the exam board thinks this is right so think this" but really this is not true. The aerials in a polarising filter absorb the waves oscillating parallel to it. They work just like a radio aerial because when the aerial is down nothing is absorbed because the radio waves have no horizontal component only a vertical one (they are polarised) but when it's up it absorbs the wave. Now if you believe the gap idea... where are the gaps in the radio aerial and why would a light polariser work any different.. light is also an EM wave (BTW light is not the only thing that can be polarised, as far as I'm aware any transverse wave can be though I really wouldn't know how unless it's an EM wave because it's the electrical field and magnetic field of the aerials that absorb just one orientation...) sooooo the wave will only be absorbed by the aerials if they are parallel to the electrical component of the wave.
P.S. If I mention the magnetic wave that's more just me applying my honestly limited knowledge because the electrical field has a much greater magnitude so it's the only one I ever hear about but IK the magnetic field is perpendicular to electrical field in both EM waves and in Flemming's hand rules.
If anything I said was explained poorly just ask.
You are right, I made a video about the truth here: ua-cam.com/video/TWu4U-ngMjk/v-deo.html
language isdifficult to understand
i think for the first time i could see his face
Anyone else here because they’re doing transition work?
I still don't understand it my dumb Brain😩😭
It’s been a year can u please say what made u get it cause I am facing the same situation
@@user-qg6io7hy6mdm me and i’ll explain fully
Jesus is king