Answer
One can use a compass placed beside the wire and observe the compass needle change direction when the battery is disconnected and then reconnected. So something must be happening in the wire. One can feel the heat emanating from the light bulb. One can use charged glass and plastic rods to find that charge does not accumulate at the light bulb. Energy is transferred somehow from the battery to the bulb. Some kind of charge carrier must flow through the wire.
Work Step by Step
One can use a compass placed beside the wire and observe the compass needle change direction when the battery is disconnected and then reconnected. So something must be happening in the wire. One can feel the heat emanating from the light bulb. One can use charged glass and plastic rods to find that charge does not accumulate at the light bulb. Energy is transferred somehow from the battery to the bulb. Some kind of charge carrier must flow through the wire.
