# Homework Help: Step Up Transformer

1. Apr 18, 2010

### sp1974

I am having a problem with the following problem: A step-up transformer increases 10V to 170V. What is the current in Amperes in the secondary as compared to the primary? Assume 100% effiiency.

The only formula I can see that has Amps in it is the turn ration I(secondary)/I(primary)=N(primary)/N(secondary)

How can I solve with out the number of turns? I know 170V/10V=N(secondary)/N(primary)

Any help is appreciated

2. Apr 18, 2010

### Stonebridge

100% efficiency means no energy/power loss.
Do you know a formula for electrical power that involves V and I?

3. Apr 18, 2010

### sp1974

Ohm's Law?

4. Apr 18, 2010

### Antiphon

Power in must equal power out. Use the equations for power when you know voltage and current.

5. Apr 18, 2010

### sp1974

All I know is the Voltage and that there is no power loss... I am looking for current

6. Apr 19, 2010

### sp1974

How about today? Can anyone offer some helpful hints to point me in the right direction?

7. Apr 19, 2010

### Stonebridge

You are not asked to find the actual current, just how it compares. So the ratio of the current in the secondary to that in the primary will be fine.
You need the formula for electrical power in terms of V and I, as has been mentioned.
It's not Ohm's Law.
You must have notes or a book with this in, as it's fundamental to this topic.

8. Apr 19, 2010

### sp1974

Yes I realize that now. I was over thinking the problem. It would be Vs/Vp=Ip/Is I believe. At least I know it would be 10/170 = .058A

Thanks for coming back to clearify for me.