The Challenge: Make an underwater flashlight
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How can we make
our own light bulb?
First, a resistor
was put in the circuit in series. The resistor was a very long bit of
wire that we knew wasn't great at conducting a current. We gradually reduced
the length used, then took it out of the circuit when we were sure it
We tested out which
wires glowed the brightest and lasted the longest. We began by using a
50cm (19.7 in.) piece of wire coiled up and gradually reduced the length until it
The shorter the length,
the more brightly it glowed but the more quickly it burnt out. To increase
the brightness we used two filaments in the same glass jar.
Filaments in the jar
Removing oxygen from the bulb