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Magnetic strength of solenoid does not alter with voltage, right?

Only current, turn density and permeability?

Reason I ask is because for this work I'm currently doing I used this soft iron square U shaped core. On either of the vertical bits were identical coils of 600 turns and a current was passed through them. I first used a powerpack for each coil but then I switched to using one powerpack and connected the two coils in parallel and the magnetic strength seemed to have waekened.

I used an accurate volt and ammeter so when using the single powerpack for both coils the different settings on the powerpack (i.e. 2V, 4V,...12V) produced a voltage drop about 1 V less than when using two powerpacks. And comparing similar currents passing through, the single powerpacks voltage drop was less and the magnetic strength was less.

I'm really having trouble explaining why the field strength was less for the latter for comparable currents. Any help, please? :smile:
Reply 1
bump? :frown:

Some of the power will be dissipated as resistive losses? This will effect strength of magnet?
Reply 2
hi jordan :smile:
(sorry for hijacking your thread!)
Reply 3
yeah stop interrupting all the help I'm getting!

(hello!)
Reply 4
I'm not sure what else it might be, but I can only recommend checking whether what you're assuming is the same is actually the same (e.g. where you're measuring the field, since it may not actually be uniform, whether the number of turns is accurate). Sorry I can't think of anything more helpful to say though...
Reply 5
Surely altering the voltage alters the current and thus.....
Reply 6
He says "comparing similar currents" though.
Reply 7
Fointy
Only current, turn density and permeability?

Reason I ask is because for this work I'm currently doing I used this soft iron square U shaped core. On either of the vertical bits were identical coils of 600 turns and a current was passed through them. I first used a powerpack for each coil but then I switched to using one powerpack and connected the two coils in parallel and the magnetic strength seemed to have waekened.

I used an accurate volt and ammeter so when using the single powerpack for both coils the different settings on the powerpack (i.e. 2V, 4V,...12V) produced a voltage drop about 1 V less than when using two powerpacks. And comparing similar currents passing through, the single powerpacks voltage drop was less and the magnetic strength was less.

I'm really having trouble explaining why the field strength was less for the latter for comparable currents. Any help, please? :smile:

It could be a simple internal resistance effect, but if you're saying you're keeping the current in the coils the same on switching power arrangements then this would not affect the magnetic field produced.

What I would advise is checking whether you are driving the current in the same direction in each coil. Looking down on the top of the verticals of the U, one coil should have current going clockwise and the other anticlockwise.

If the currents are in the same sense looking at the magnet like this, then you will get a weaker field than if they are in opposite senses.

If you're confused, imagine straightening out the U into a bar. The current must go the same way around the bar all along its length. Or consider that magnetic field lines come out of one end of the U and go into the other, thus by right-hand grip rule, the currents must be flowing in opposite senses.
Reply 8
I want to do some home made practical on producing alternating current,how can i do that?
Reply 9
Morbo
It could be a simple internal resistance effect, but if you're saying you're keeping the current in the coils the same on switching power arrangements then this would not affect the magnetic field produced.

What I would advise is checking whether you are driving the current in the same direction in each coil. Looking down on the top of the verticals of the U, one coil should have current going clockwise and the other anticlockwise.

If the currents are in the same sense looking at the magnet like this, then you will get a weaker field than if they are in opposite senses.

If you're confused, imagine straightening out the U into a bar. The current must go the same way around the bar all along its length. Or consider that magnetic field lines come out of one end of the U and go into the other, thus by right-hand grip rule, the currents must be flowing in opposite senses.

No its definitely not that, I original accidentally put the coils the wrong way round, it caused the magnetic field to almost completely cancel out.

Can just confirm tho, that say you have two identical coils, except one has a very high voltage and a very high resistance, the other has barely any voltage but also tiny resistance, so that both coils have exactly the same current, their respective magnetic fields will be identical? yes?

I might be able to try and explain the difference as a result of some other change then.



roshanhero
I want to do some home made practical on producing alternating current,how can i do that?

Make a new thread. This is not the place to discuss this.
Reply 10
Fointy
Can just confirm tho, that say you have two identical coils, except one has a very high voltage and a very high resistance, the other has barely any voltage but also tiny resistance, so that both coils have exactly the same current, their respective magnetic fields will be identical? yes?

Yes, look at the equation: B=μNLIB = \mu \frac{N}{L} I.

I might be able to try and explain the difference as a result of some other change then.

How about you post some figures and data, and maybe we can help. It might be because you're using the wrong kind of current meter or something.

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