13. a transformer has a primary coil with 600 turns and a secondary coil with 300 turns. if the output voltage is 320 volts, what is the input voltage? (1 point).

His is a step down transformer since n(primary) is greater than n(seconcary). You relate the input voltage with the ouput voltage with the following equation: 

Vout = n2/n1*Vin (n2/n1 is essentially your 'transfer function' that dictates what a specified input would produce) 

Solving the equation: 

Vin = Vout*n1/n2 = (320V)*(600/300) = 640 V 

This is checked by seeing if Vin is greater than Vout, which it is for a step down transformer.