Hello I am Jared, welcome to Fun Science Demos. You know, here at Fun Science Demos, we like to say that science is at work all around us. You just have to slow down
take a closer look to find it. Something as simple as a pencil, a glass
of water, has a lot of science in it. Check this out.
I am going to take the pencil, put it in the glass of water and take a closer look at
what happens. So take a look at my glass and my pencil, it almost looks like the
pencil is cut in half. So what is going on? Well, science is going on!
The pencil has not changed, so why does it look like it has been broken in half? Well, first we have to figure out how we see things.
Through science, we have discovered that we are able to see objects around us
because light bounces off of those objects and goes into our eye. We see things because of light.
When light travels through air it travels really, really fast but when light travels through something
like water, that water actually slows the light down and it
does something to that light when it slows it down. well through science we have
discovered that when light travels through water it gets slowed down and
because it slows down it actually bends. that is why this pencil seems to be
broken so to take a closer look at the idea that light slows down and bends
when it goes through water. well, we got ourselves a bigger container of water
and we are going to let this pencil act like light. we are going to hold it above and
drop the pencil. we are going to see how the pencil moves through the air and then
how it moves through the water and see if there is a difference between the two.
so I am standing up above our container. I am going to drop the pencil straight. take
a close look at how the pencil travels through the air and then watch what it
does when it hits the water. here we go
so as the pencil fell through the air it fell straight and when it hit the water
it slowed down and when it slowed down the path of the pencil bent in the water.
that is exactly what light does. next we are actually going to try and show you
light being bent, but to do that we need to use a special kind of light.
Scientists call it a laser. Remember that most light, like sunlight or light from
light bulbs, is scattered all around but this light is focused into a
single beam so it is really important to never point this in your eye because the
light from this laser is not scattered and it is focused in a single beam. We can
actually see its path if we shine it through the right material and the right
material happens to be lemon flavored jello. We are going to turn the lights off
and zoom in and take a closer look and see what happens
to the path of this light in this laser when we pass it through the lemon jello.
so we have zoomed in, I have my laser, I have my lemon jello. let us see if we can
see the path the light travels. and you can see my red laser goes right through
the jello. now let us see if we can actually bend this light because it
slows down as it goes through the jello. and take a closer look and see if we can
get to see the light actually being bent. so we have zoomed in, I have my laser and I
have my dish of jell-o, and now to show you the bending of that light I am going to
first shoot the laser above the jello in a straight line and hit somewhere around
this arrow, then I am going to shine that laser through the jello and that jello
should slow that light down and bend it and move it over somewhere around here.
so here we go I'm going to shine the laser at the dot, not through the jello. now I am
just going to drop it down through the jello and you can see it move over back
and forth through the jello. the light bends and now it is hitting over here.
it is hitting there in a straight line but when it goes through the jello you
can see it bending. it's path bends and the light has actually moved over. that is
exactly why the pencil seemed broken. the water was bending the light
by slowing it down. as this light travels through the jello it slows down and
bends and gets moved over. if we look even more carefully we are going to notice
there is a whole lot of bending going on. it gets bent once as it goes into the
jello, as I follow that line but then as it exits the jello it gets bent again.
that is a lot of bending going on and that light is being bent as it slows
down, as it travels through the jello. something as simple as a pencil and a
glass of water can teach us an awful lot about the science behind light. science
is all around us, light is all around us, and sometimes we just need to stop and
try to wonder why. if you want to learn more about light check out our links.
thanks for watching.