A Bear Sentry is an example of a simple electrical circuit.
The fence polywire is connected to the positive ( + ) terminal of the energizer; all the lines are ( + ). The ground stake is connected to the negative ( - ) terminal of the energizer; all of the campsite ground underfoot and paw is ( - ).
The Bear Sentry is an open circuit
when there is no connection between the ( + )
and ( -
) poles of the energizer. Nothing happens.
When an electrically conductive body like a bear contacts the polywire, it becomes the missing link between the fence (positive) and the ground (negative).
The bear completes the circuit between the ( + ) and ( - ) poles of the energizer.
A huge pulse of electrical energy flows from nose to paws to ground for a split second. Shocked, the bear runs away.
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