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# AS wire resistance question Watch

1. circuit EMF 2V, has a rheostat and wire in series. The wire is 3.4 ohms, and rheostat goes from 0-1500ohms

Asks to calculate the maximum and minimum p.d. that the wire can have.
I understand that maximum p.d. is 2, but i figured minimum would be 3.4/1503.4, however the MS says that it has to be 2x(3.4/1503.4). Why does it have to be doubled?
2. (Original post by Deathlotus)
circuit EMF 2V, has a rheostat and wire in series. The wire is 3.4 ohms, and rheostat goes from 0-1500ohms

Asks to calculate the maximum and minimum p.d. that the wire can have.
I understand that maximum p.d. is 2, but i figured minimum would be 3.4/1503.4, however the MS says that it has to be 2x(3.4/1503.4). Why does it have to be doubled?
You have correctly stated the ratio between the resistances as

This must now be multiplied by the source voltage to get the actual p.d. developed across the wire:

Hence:

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