With my students I normally use a measuring cylinder filled with water impregnated with a bit of pink highlighter fluid and a green laser. It fluoresces yellow and looks fantastic!
I kept scratching my head as to what was going on when the bottom was revealed and then realized this was posted on April 1. Well played, Harvard, well played
Thanks! It’s my own design, with a FET that switches on the LEDs when the water covers two nickel foil strips. I’ll put that on the list of behind-the-demo videos to make.
If the light is completely trapped inside the stream of water, why do we see the red color of the laser in the stream? That means some of the light is escaping from the stream, doesn't it?
Yes you are correct, to make the demonstration more visible to the audience we add a couple drops of milk to the water so that some of the light scatters off to the side of the water flow.
No, that part of the demo is actually a prank-the bucket is illuminated by LEDs that we wired to the bottom of it to make it seem like the light is stored in the bucket, in violation of conservation of energy. The illuminated stream of water, however, is a real phenomenon.
Yes there are battery powered LEDs that automatically turn on when water is added to the bucket. Their purpose is to provoke questions and discussion about wether the laser light will keep reflecting around inside the bucket after the stream of water has stopped, resulting in a "bucket of light."
This is beautiful. Can I use a part of this footage especially from opening the bottle cap to water flowing down? Of course, credits will be given on video and description.
Natural as the water runs out the pressure is reduced. Question: even though the light source maintains the correct angle of acceptance. Why does the light follow the flow almost all the way? I noticed at the end when the light falls out of the water stream. Looks very nice in slow motion. Is this because the angle of reflection is grater than the angle of refraction?
The short answer is that every time the laser light inside the stream of water encounters the inner wall of the stream (i.e. the water-air interface) the angle of incidence with that interface is less than the critical angle needed for total internal reflection. For more explanation, see hyperphysics.gsu.edu/hbase/phyopt/totint.html and sciencedemonstrations.fas.harvard.edu/presentations/bucket-light
Girl really? Why would you make you question the light inside the bucket. I was pissed because I actually thought for one hot second light actually stayed in the bucket. LMFAo
Air flow. Ever pour Any liquid out of a bottle or jug and it goes "glug glug glug" ? That’s Because there's not enough air going in to allow the liquid to come out. Put a straw into the bottle so the inside end of the straw is an air pocket and then the liquid will flow out smoothly. Science 101.
With my students I normally use a measuring cylinder filled with water impregnated with a bit of pink highlighter fluid and a green laser. It fluoresces yellow and looks fantastic!
That light of the bucket keeps my attention over 10 min (double time of this video), What a trick!
you had me with the LED! hahaha, great demonstration thank you!
What is your Instagram id
nvrgonagiveuup
I kept scratching my head as to what was going on when the bottom was revealed and then realized this was posted on April 1. Well played, Harvard, well played
i like the little magic trick at the very end, Daniel! :)
Thanks! It’s my own design, with a FET that switches on the LEDs when the water covers two nickel foil strips. I’ll put that on the list of behind-the-demo videos to make.
Oooof...That water pouring out of the bucket looks like knowledge pouring out of my brain
If the light is completely trapped inside the stream of water, why do we see the red color of the laser in the stream? That means some of the light is escaping from the stream, doesn't it?
Yes you are correct, to make the demonstration more visible to the audience we add a couple drops of milk to the water so that some of the light scatters off to the side of the water flow.
nice observation
Elegant presentation!
Well played! Thumbs up!
That soda bottle looks about as 80s vintage as that HeNe!
you are correct!
amazing , thanks for the experience
Why is the water still shining after landing in the bucket? Does that mean we can store light in a bucket like that?
No, that part of the demo is actually a prank-the bucket is illuminated by LEDs that we wired to the bottom of it to make it seem like the light is stored in the bucket, in violation of conservation of energy. The illuminated stream of water, however, is a real phenomenon.
Amazing. So much to learn.
Who else needs to pee now?
I came here to explain my job to people, and now I have to pee.
Are those lights at the bottom of the bucket and why are they there? What purpose do they serve? I have questions and need answers.
Yes there are battery powered LEDs that automatically turn on when water is added to the bucket. Their purpose is to provoke questions and discussion about wether the laser light will keep reflecting around inside the bucket after the stream of water has stopped, resulting in a "bucket of light."
They prompted questions in my mind for sure! So does the light continue to reflect in the water in the bucket?
@@NatSciDemos So is the answer yes since the color didn't change?
Lmao this is enough to fool my non-science background friends 😂
Wow beautiful phenomenon
Happy April fools day !!
The light is still in the bucket?...woww
This is beautiful. Can I use a part of this footage especially from opening the bottle cap to water flowing down? Of course, credits will be given on video and description.
Good video
After the bottle got empty , why water in bucket is glowing sir.
It is a prank.Check the date of uploading
Just mind blown
Cool! Thank you!
Trapping light near indefinitely will be one of the biggest achievemnts of mankind
Thank you
Haha, this isn't the concept of total internal reflection, this is the glowing water in real! 😀
Wow... thanks a lot
You should have used a yellow laser.
Why that bucket is glowing red after water flow stopped
we hid a flashlight in the bottom of it
Darth Vader peeing...
Natural as the water runs out the pressure is reduced. Question: even though the light source maintains the correct angle of acceptance. Why does the light follow the flow almost all the way?
I noticed at the end when the light falls out of the water stream. Looks very nice in slow motion. Is this because the angle of reflection is grater than the angle of refraction?
The short answer is that every time the laser light inside the stream of water encounters the inner wall of the stream (i.e. the water-air interface) the angle of incidence with that interface is less than the critical angle needed for total internal reflection. For more explanation, see hyperphysics.gsu.edu/hbase/phyopt/totint.html and sciencedemonstrations.fas.harvard.edu/presentations/bucket-light
Wow ,super activity
Where are your laser safety glasses?
why is the bucket still lit up in red after the experiment?
You should read the description :)
@@mjk0104 haha indeed, or watch the video to the end, my bad!
What are those in the bottom of the bucket and why?
Is it possible to use bent acrylic tube to redirect sunlight to a shaded place?
Yes.
So now we can route lasers inside of water - just when we thought squirt guns were safe toys.
Nice
What?? 1:27
Is there a source of light inside the bucket!!
Girl really? Why would you make you question the light inside the bucket. I was pissed because I actually thought for one hot second light actually stayed in the bucket. LMFAo
Why does the water pour out of the hole in the bottle only after the cap is removed?
Air flow. Ever pour Any liquid out of a bottle or jug and it goes "glug glug glug" ? That’s Because there's not enough air going in to allow the liquid to come out. Put a straw into the bottle so the inside end of the straw is an air pocket and then the liquid will flow out smoothly. Science 101.
@@Kristinapedia science 1001
We need to see how far the TIR of the laser in the water goes down.
Not totally reflected. I still see light leaking out from the water flow. If totally reflected, we shouldn't see the light, right?
To make the demonstration more visible we added a few drops of milk to the water, which scatters the light from within the liquid.
Diagnosis: hematuria.
I am going to create a Hindu meditation spa with showers and falls that do that.
5 year old me at 2am at my friends birthday party sleepover after I drank all the red glowsticks
What would happen to the laser beam if the bucket was a fish tank full of water
In that case the laser light could reach the bottom of the tank and reflect (at least partially) off of whatever's there.
@@NatSciDemos that’s pretty cool that means light can be completely redirected. What if you shined a bunch of lasers at the hole in the top.
Anybody else need to pee now?
Now I gotta pee.
very cool
Someone explain the ending part where the bucket is shining
The flashlight in the bucket is a prank to make it seem like the laser light has been captured in it.
Awesome
LMAO! Excellent!
Why the "few drops of milk"? Is that just to add a little opacity so the color show up better?
Basically yes--the milk scatters the light off to the side so that we can see it better.
👏👏👏👏👏
Go to the bathroom before watching this.
1:29 why is the bucket still glowing red?
Ha Ha NICE!
Lol.. i got prank
Who's from alan walker ?
Neon piss
Наука епта.
Why the LED trick in the bucket? A serious experiment marginalized by showmanship. Too bad the "scientist" isn't serious...
The red LEDs in the bucket ruin this video. Faking things is NOT a good way to do science demos!
What's wrong with a little humor in a science demo? Don't be lame.
НАХУЯ!?