Quick question (1 Viewer)

[FrozenSky]

Ok soo our teacher gave us a question and i know it's 100% sure that it's in the test.. But tbh i think the question is a bit stupid.. Anyway it would be very much appreciated if anyone may help.

" Discuss the proposition of vp/vs = np/ns as an equation of a model for transformers "
(4 marks)

Basically the teachers wants the advantages and disadvantages of this equation being used as a model for transformers...

So far i got two points:

- It's simple
- It doesn't take into account of power loss

Any suggestions? Even advantages of a model in general would be good.

Thanks

 

[adomad]

low voltage means higer current... so thicker cables are needed? i agree, stupid question

say that that formula iss for an 'ideal' transformer... some energy is lost due to heat

 

[FrozenSky]

low voltage means higer current... so thicker cables are needed? i agree, stupid question

say that that formula iss for an 'ideal' transformer... some energy is lost due to heat

Yeah it's really frustrating because my test is tomorrow... When i first read it i interpreted the question as, discuss how the formula acts as a model for transformers. But when i asked the teacher to explain this question to me she told me to go through the adv/dis of the model...
So basically what are the advantages and disadvantages of using a model in general, heck it doesnt it have to be a model of transformers. Very stupid question...

Anyway thanks for trying to help

 

[adomad]

disadvantage: some noob might not compensate for the power loss...

 

[darkchild69]

" Discuss the proposition of vp/vs = np/ns as an equation of a model for transformers "
(4 marks)

Basically the teachers wants the advantages and disadvantages of this equation being used as a model for transformers...

So far i got two points:

- It's simple
- It doesn't take into account of power loss

Any suggestions? Even advantages of a model in general would be good.

Thanks

Geez, i dunno!?!?

Some stuff to consider could be:
- Leakage flux
- Energy losses due to eddy currents
- Energy losses due to resistance of copper windings
- Effect of frequency on EMF
- The Equation you were given suggests that transformers can work with DC and all frequencies of AC. The equation itself stems from:
-- Vp = Np (d0/dt)
-- Vs = Ns (d0/dt)

In these equations, there must be a change in flux in order for the Voltage to be produced, but in the equation you were given, it does not specify.

I am not too sure on what else to say?

 

[FrozenSky]

The Equation you were given suggests that transformers can work with DC and all frequencies of AC\

tyvm that helped for dis

 

[darkchild69]

Good stuff!

Let us know how u went when u get the results

 

[FrozenSky]

Good stuff!

Let us know how u went when u get the results

Omg... im really disapointed with my results ==''....

16.5/20 *sighhh

Our teacher who is on holidays right now (another teacher marked the test) returning next Monday gave me the wrong answers.. I freaken asked her what's the independent variable for the transformer experiment, and she told me input voltage. I then asked but can't it also be coils? "NO NO NO JUST INPUT VOLTAGE" Then i saw that question in the test and knew it was coil but i wrote input voltage because my teacher said so and i lost freaken two marks ==''... Im going to soo argue those two marks, i believe i should be compensated she told me the wrong answer...
Btw i haven't looked at test yet, but im guessing i probably lost 1 mark for the VP/VS=NP/NS thing :/ Will inform you more about my test results when my teacher comes back and see what she has to say for herself ==''.........

 

[darkchild69]

Really, either could be considered independent variable, depending on the experiment.

Eg, if you are measuring how secondary voltage changes when you change input voltage then the indep in the input voltage

However, if you are determining how the secondary voltage changes when you increase/decrease the ratio of primary:seconday coils, then the indep in the coils

 

[FrozenSky]

Yeah.. i knew it was coils but what the teacher said was etched into my head.. Oh wells goes to show that you can't believe everything a person say. Anyway i looked at my test and found that i lost a mark on the question i asked here. I lost a mark because i didn't state what a model is :/...