Posted by **TJ** on Monday, August 3, 2009 at 11:00pm.

A transformer has a secondary voltage of 12 V. The primary voltage is 60V. The number of turns in the secondary is 100. How many turns are in the primary?

I keep getting 200 using the equation Vs/Vp= Ns/Np

the answer is 500... what am i doing wrong

- Physics -
**DrBob222**, Tuesday, August 4, 2009 at 12:01am
I don't know about the equation but if the secondary is 12 and primary is 60, then the primary must have more turns. If the secondary is 100 turns, then we multiply 100 x factor and the factor must give us a number higher than 100, so that is 60/12.

100 x (60/12) = 500 turns.

Using the formula,

Vs=12

Vp=60

Ns=100

Np = ?

(12/60) = (100/x)

and that gives me

12x = 60*100=60,000

x = 60,000/12 = 500

You must not be solving the proportion correctly.

- Physics -
**TJ**, Tuesday, August 4, 2009 at 12:08am
Thanks that helps alot i don't know why i was using 24 for Vp

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