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Motors and Generators Questions (1 Viewer)

x.Exhaust.x

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Hey, can anyone help me out with the following Motors and Generators questions?

1. What are some advantages/disadvantages of the effect of transformers on electrical transmission, and in the home?

I know power loss is one, by stepping up the voltage, which decreases the current and therefore minimising power loss. What else?

2. In AC the direction of the current flow charges every 1/2 turn of the coils.

a) Devise an experiment that you could perform to investigate the production of AC.

Do any of the HSC 08'ers have a summary practical on this, with the method, results, and conclusion? I have yet to to do the practical for motors at school.

3. AC supplies to the home are 'rectified' inside most electronic appliances. Rectification means ensuring the current, and thus the emf only flows in one direction, in a sense this stimulates DC.

i) Draw the rectified emf vs. time wave, and explain why it only stimulates DC.

I know that the emf. vs. time graph looks like a sine curve. But I'm not sure about the rectification of the graph (how it looks), and the stimulation on direct current.

4. What are some uses/appliances of DC generators? :jedi:

5. Transformers are found in many applications such as phone chargers. A particular phone charger has a primary voltage of 240V and a secondary voltage of 12V, and current of 0.1mA. The primary coil has 100 turns.

a) Assuming the transformer is ideal, calculate the power output of the charger.
b) Calculate the current in the primary coil.
c) If the primary coil was supplied with a 45Hz AC signal, what would be the frequency in the secondary coil?

6. Evaluate whether installing DC power supplies in Data centres is a viable option.

I hate research questions (If you cbb researching, don't bother lol :haha:). I have so far (if it helps):

Installing DC power supplies in Data centres is a viable option as problems in computers are actually caused by malfunctions in the transformers in power supplies and not the computer themselves.

7. Evaluate the effect of transformer on electrical transmission, and in the home.

Thanks guys :D
 

Arowana21

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i will give some brief answers as i have now sorta forgotten most of this stuff..lol.

1. It surely does minimise powerloss when you increase voltage since P=I^2 * R
And also i THINK, but there is also slight power loss through the induction of eddy currents which thus produces heat in the iron core of the transformer which is a disadvantage.
(Cant think of anything else at this moment, sorry...)

2. do it at school or google physics notes.

3. it is just [sin@] graph. ([] = absolute value)

4. I think DC is used in small appiances that require small and STEADY voltage, like fans, calculaters etc.

5. a) P= VI, u work it ur self and remember to convert mA to A.
b) Vp/Vs = Np/Ns = Is/Ip, USE THIS RULE where V=voltage, N=number of turns, I=current, p=primary and s=secondary.
c) i am not to sure

6. SCrew it

7. Like the first q
 

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