Can you crush a can? Or launch it in the air?
The Demonstration: A soda can
is launched into the air using a giant electromagnet. Change the
starting position and the can is crushed. Be sure to cover your ears!
Quick Physics: The
electromagnet has a strong enough magnetic field to turn the can into
an electromagnet as well. The two magnets repel and the can is
launched! If it has no where to launch, the can is crushed by the force
of the magnetic field.
The Details:
The can crusher is a giant electromagnet. A wire comes from the
capacitor, which is like a big battery. Then the wire wraps around in a
coil to make an electromagnet. The coil becomes a very strong magnet
when the can crusher is turned on. It is thousands of times stronger
than the earth’s magnetic field and its strength can be used to crush a
metal can.
When we put a can in the coil and turn the can crusher on, electricity
flows through the coil. Also, some of the electricity flows around the
outside of the can. Like the jumping ring, the can crusher has two
electromagnets: the coil and the can. We know that magnets repel each
other if they point the same way. The can is repelled by the coil from
all directions. Since the can is inside the coil, the sides of the can
get pushed away from the coil. This crushes the realtively soft metal
can. We can also put the can on top of the coil instead of inside it.
Now the bottom of the can is repelled by the top of the coil. Instead
of crushing the can, it goes shooting off into the air like a rocket.
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Link to Teacher Resources
Page Updated 8/29/07