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# Dynamo effect - current watch

1. So when you move a magnet through a coil (or wire with lots of coils), it increases the current (I think).

1) Would it always need to be hooked up to a power supply in order to work and generate electricity via the dynamo effect (the wire that is)

2) If it is hooked up to a power supply, how can it generate a higher current by the more coils in the wire or the stronger magnet, when the voltage would be the same? How is it possible for the current to increase when the voltage stays the same when you add more coils or use a stronger magnet?

thanks
2. (Original post by blobbybill)
So when you move a magnet through a coil (or wire with lots of coils), it increases the current (I think).

1) Would it always need to be hooked up to a power supply in order to work and generate electricity via the dynamo effect (the wire that is)

2) If it is hooked up to a power supply, how can it generate a higher current by the more coils in the wire or the stronger magnet, when the voltage would be the same? How is it possible for the current to increase when the voltage stays the same when you add more coils or use a stronger magnet?

thanks
1) No, it would not need to be connected to a power supply in order to induce current. It would actually induce current even if the wire wasn't connected to anything but in order to detect the current it needs to be connected to a ammeter or something like a bulb that would light up when electricity is generated. If it is hooked up to something supplying it with electricity, it defeats the point of it generating electricity.

2) Like I said before it doesn't need to be hooked up to a power supply. However, the voltage can stay the same while the current increases, just the power would increase as P=IV. If the power remains constant then the voltage would have to decrease if the current increased.

3. (Original post by blobbybill)
So when you move a magnet through a coil (or wire with lots of coils), it increases the current (I think).

1) Would it always need to be hooked up to a power supply in order to work and generate electricity via the dynamo effect (the wire that is)

2) If it is hooked up to a power supply, how can it generate a higher current by the more coils in the wire or the stronger magnet, when the voltage would be the same? How is it possible for the current to increase when the voltage stays the same when you add more coils or use a stronger magnet?

thanks
if you're using a permanent magnet you don't need any power supply connected.
4. (Original post by Midnight Star)
1) No, it would not need to be connected to a power supply in order to induce current. It would actually induce current even if the wire wasn't connected to anything but in order to detect the current it needs to be connected to a ammeter or something like a bulb that would light up when electricity is generated. If it is hooked up to something supplying it with electricity, it defeats the point of it generating electricity.

2) Like I said before it doesn't need to be hooked up to a power supply. However, the voltage can stay the same while the current increases, just the power would increase as P=IV. If the power remains constant then the voltage would have to decrease if the current increased.

So if the current increased whilst connected to a power supply due to an increased magnetic strength or more coils, and the power would therefore have to increase as P=IV, how can the voltage decrease if you set it to something like 6V on the power supply? Or can it decrease anyway even if you put it to something like 6v?
5. (Original post by blobbybill)
So if the current increased whilst connected to a power supply due to an increased magnetic strength or more coils, and the power would therefore have to increase as P=IV, how can the voltage decrease if you set it to something like 6V on the power supply? Or can it decrease anyway even if you put it to something like 6v?
You wouldn't connect it to a power supply as the dynamo itself is the power supply in this circuit. It doesn't need to be connected to be connected to a power supply. I suppose if you did it would be similar to having a circuit with two batteries in it. I was just making an aside point before that it was possible to increase the current while the voltage remains constant if the power increases, which having a dynamo induce current would increase the power. Sorry if I confused you.
6. (Original post by blobbybill)
So when you move a magnet through a coil (or wire with lots of coils), it increases the current (I think).

1) Would it always need to be hooked up to a power supply in order to work and generate electricity via the dynamo effect (the wire that is)

2) If it is hooked up to a power supply, how can it generate a higher current by the more coils in the wire or the stronger magnet, when the voltage would be the same? How is it possible for the current to increase when the voltage stays the same when you add more coils or use a stronger magnet?

thanks
So you have a coil of wire with a constant voltage dc power supply connected at the ends? You're moving the magnet into or out of the coil?

This may increase or decrease the current in the wire, depending on which way you move the magnet(I guess it's impossible to explain this at GCSE).

1) As others have said.

2) Adding more coils or using a stronger magnet will increase the induced voltage(I guess it's impossible to explain this at GCSE). You could change the current without changing the induced voltage by using a lower resistance wire for example.

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