Transformer – energy cannot be lost or gained

Now we know that doubling the coils doubles the voltage and therefore:

$V_1/V_2=(Number\ \turns\ \1)/(Number\ \ turns\ \2)$

We must also remember that:

Power can not be lost or gained

If $Power=VI$ and power can not be lost or gained it follows that if voltage is increased, current is reduced and vice versa. Remember:

$V\o\l\t\a\g\e\ \1xxCurrent\ \1=Primary\ \Power=S\e\c\o\n\d\a\r\y\ \Power=V\o\l\t\a\g\e\ \2xxCurrent\ \2$

(NOTE: Secondary power is slightly less due to small inefficiencies, but they are ignored here)

This is an easy way for you to remember that:

$V_1xxI_1=V_2xxI_2$

	1000 v and 1 Amp equals 1000 watts 1 volt and 1000 Amps equals 1000 watts 500 v and 2 Amps equals 1000 watts 5 v and 200 Amps equals 1000 watts

Therefore because

$V_1I_1=V_2I_2$

$V_1/V_2=I_2/I_1$