to the image on the next slide.
Can sound travel through a solid?
Do you remember what a solid IS?
about 6 feet or 2 meters
to make a small hole
in the bottom
of the cans or cups.
through each hole
and knot each end
of the string inside
the cans, as shown.
Make sure the
KNOTS are BIG.
the full length
between two people.
BE SURE the string
is TAUT.
while the other one places the second can over his/her ear.
Take turns speaking and listening. Do you feel the vibrations?
a physical medium.
Did sound travel through the string
Definitely.
And you made
a tin can telephone
to prove it.
Congratulations!
been known for centuries!
For a short time, these acoustic telephones actually competed
with the FIRST electrical telephones.
The maximum range of the tin can telephones was limited,
but hundreds of innovations
increased that range
to as far as 3 miles (4.8 km).
than through air.
Trackers and hunters
often press their ears
to the ground to better
hear the footsteps
of people or the
hoofbeats of animals.
Try it!
or balloon
or twist tie
Through Liquids?
the plastic bag
or balloon
with water.
rubber band
or twist tie
to seal in
the water.
ear with their free hand.
The speaker talks
through the bag.
a physical medium.
Does sound travel through a liquid
Definitely.
Sound travels through a liquid.
What do you think?
HINT: When you speak,
do others hear you?
in the air.
When you speak and when you
bang the spoons together,
the sound is transmitted through
the gases in the air to your ears.
through the mediums of solids, liquids and gases.
What about a vacuum?
A vacuum is empty space,
the absence of any medium.
If you were in outer space
or standing on the Moon,
COULD you hear a sound
through the emptiness
of space which is
a near vacuum?
can travel in a vacuum by ringing
a bell in a vacuum chamber.
What IS a vacuum chamber?
It is an enclosure where almost
all of the air has been SUCKED
OUT using a vacuum pump.
The bell could be heard ringing inside the air filled chamber.
A vacuum pump was
then used to remove the air
from the chamber.
through a solid
through a liquid
through a vacuum
a medium
it has too few particles
to vibrate.