# Calculation On Transformer

1. Mar 19, 2012

### chikis

1. The problem statement, all variables and given/known data

Hello everybody, am confronted with this question:
A transformer with 5500 turns in its primary is used between a 240V a.c supply and a 120V kettle. Calculate the number of turns in the secondary.

2. Relevant equations

The equation Es/Ep = Ns/Np can be applied in solving the problem.
Where Es = e.m.f of secondry. Ep = e.m.f of primary, Ns = number of turns in secondary coil, Np number of turns in primary coil

3. The attempt at a solution

Using the formular:
Es/Ep = Ns/Np
Where Np = 5500turns
Ns = ? becuase am required to calculate for it.
For Es and Ep, I don't know the value to substitute in for Es and Ep respectively. Whether is the 240V or 120V. I don't know between 240V and 120V the one that is Ep or Es respectively.
I can't go further with the calculation since am unable to substitute in the values into the equation correctly. Can sombody help me here please?

2. Mar 19, 2012

### tiny-tim

hi chikis!
the coil with the electricity source going through it is always the primary

3. Mar 27, 2012

### chikis

Thank you very much tiny-tim,
that answer have solved my problem. I will work the problem and forward the working in for all to view. Thank you once again, am very greatful.

4. Mar 27, 2012

### chikis

Thank you very much tiny-tim,
that answer have solved my problem. I will work the problem and forward the working in for all to view. Thank you once again, am very greatful.

5. Mar 31, 2012

### chikis

Here is the working:
Ep/Es=Np/Ns
=240/120=5500/Ns
:.
Ns=5500*120/240
=2750
My thanks goes to tim-tim who has contributed immensly to this thread.

6. Mar 31, 2012

### tiny-tim

yes that's fine!

7. Mar 31, 2012

### chikis

Thanks for that compliment.