Transformer Problem Help

[candyq27]

Homework Statement

In some places, insect "zappers," with their blue lights, are a familiar sight on a summer's night. These devices use a high voltage to electrocute insects. One such device uses an ac voltage of 4270 V, which is obtained from a standard 122.0 V outlet by means of a transformer. If the primary coil has 23 turns, how many turns are in the secondary coil?

Homework Equations

E=-NAcos0(B/t)
V=IR
I=(V-E)/R
-B/T=V1/N1=V2/N2
V1/V2=N1/N2
I2/I1=N1/N2

The Attempt at a Solution

I'm confused about how to do this problem. I know all those formulas but I'm not sure which one to use. I'm not sure which voltage to use and what the two voltages would be. Please help. Thanks!

 

[marcusl]

You are given two voltages (primary and secondary) and the number of turns on the primary winding. Use the formaula that contains a voltage ratio and a turns ratio to find the number of turns on the secondary.

 

[berkeman]

Hint -- use your 2nd to last equation. You are given a voltage ratio, and you need to calculate the required turns ratio.

 

[berkeman]

Doh! marcusl beat me to the punch!

 

[marcusl]

Fastest typing hands in the west!

 

[candyq27]

Thanks
so is the primary voltage the 122 or the 4270?
The equation is either 122/4270=23/x x= 805 OR
4270/122=23/x x= 0.657

The 805 turns makes more sense so that must be right. Thanks!

 

[berkeman]

(listens for the sound of marcusl's keyboard...)

Yes, you are making a step-up transformer. The primary is usually the input side of the transformer, and the secondary is the output side. Your intuition is correct.

 

[marcusl]

I was sleeping that time, Berkeman :zzz: