Transformers

[naved_s9994]

Can anyone please explain Transformers in General :

Also What happens when there are more turns at primary than secondary (vice-versa)
 and general facts of transformers

Also whats the difference when in Q's theres some 'x amount RMS', and in the same question theres some 'x amount V' - like what do you do? what do they mean?

Thanks heaps !

[Flaming_Arrow]

if there's more turns on the primary than seconday it means its a step down transformer(steps down voltage, steps up current)

[kurrymuncher]

When there are more primary turns than secondary, the voltage will be stepped down. If there are more secondary turns than primary, then the voltage will be stepped up.

Transformers are used to reduce the power lost over transmission lines, eg between a generator and a city. Once the electricity is generated, it will travel through a step up transformer, which will increase its voltage to a much larger voltage. This massive increase in voltage will reduce the current in the wire. As the current is lowered, the power loss is minimised, as Ploss=I^2R. This voltage can then be stepped down to 240 volts, so it can be used in homes (lighting etc). Basically, transformers are used, as they are cost efficient. The only other ways to reduce power loss, would be to increase the resistance of the cables, but this would be nearly impossible, as it would cost ZILLIONS of dollars. Or the length of the transmission lines could be decreased but then again, this is not practical. Thats why transformers are efficient, they do not cost as much, and effectively reduce power loss.

[naved_s9994]

Ahh thanks KM and F_A !!

Also, Ideal transformer Non Ideal Transformer?

[kurrymuncher]

Ideal transformers are 100 % efficient, meaning that no power is lost. If you want to check if a transformer is ideal, just touch it. If it is hot, that means power has been lost( electrical energy has been converted to heat energy). If it isn't hot, then it is ideal.

[TrueTears]

Non ideal transformers tend to use power due to eddy currents in the iron core.

[naved_s9994]

I.E TT, you mean ideal transformers, do NOT use power?

[kaanonball]

I.E TT, you mean ideal transformers, do NOT use power?

They mean that, and ideal transformer does not lose any power as a result of excess heat generated by the coils or as TT was saying due to eddy currents.

So the power generated in the primary coil = power generated in the secondary coil

[naved_s9994]

I.e does this also mean that in an ideal transformer

V1 = V2
I1 = I2
N1 = N2 

?

[Flaming_Arrow]

[TrueTears]

I.E TT, you mean ideal transformers, do NOT use power?

...
...
If there is a current and voltage... how can there be no power?

[appianway]

I think he means no power is dissipated. After all, the formula P = VI refers to the voltage drop across two points and the current flowing.

[kaanonball]

I.e does this also mean that in an ideal transformer

V1 = V2
I1 = I2
N1 = N2 

?

In response to your question, and are different, as the transformers purpose is to change the value of , either stepping it up(increasing its value) or down(decreasing its value). otherwise there would be no point using a transformer.

and are also different, as a consequence of changing the value of voltage in an ideal transformer the values of current will be altered so that keeps true

and must be different in order to step up/down voltage/current, otherwise the induced current/emf in the secondary coil would be the same as the supplied emf/current in the primary coil

for further clarification

the term 'ideal' only refers to power, so an 'ideal' transformer is 100% efficient, hence no loss of energy.

this means

[/0]

Yes, do not use unless the question states the transformer is ideal.