## Dynamo to charge battery using electromagnet.

1. The problem statement, all variables and given/known data

A team on The Apprentice have to come up with a new electrical device. They propose a hand cranked dynamo to charge a battery which initially uses the residual charge in the battery to power the electromagnet, instead of a permanent magnet (the idea being that this reduces the weight of the device by removing the need for an iron core). Once current is flowing this is then used to power the electromagnet as well as charging the battery. A sketch of the circuit is shown in the attachment. Making reasonable assumptions about its size, the number of turns in the induction coil and in the dynamo coil, discuss the feasibility of the device. (I can't upload the sketch here, but basically it has the dynamo coil, the dynamo and the circuit resistance all in series)

2. Relevant equations

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution
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 Tags dynamo, electromagnet, induction