Question

The primary of a step-up transformer is connected across the terminals of a standard wall socket, and resistor 1 with a resistance r1 is connected across the secondary. the current in the resistor is then measured. next, resistor 2 with a resistance r2 is connected directly across the terminals of the wall socket (without the transformer). the current in this resistor is also measured and found to be the same as the current in resistor 1. how does the resistance r2 compare to the resistance r1? answers

Answer 1

The turns ratio is the factor that determines voltage andcurrent. In order to have the same current across the resistorin the primary as the resistor in the secondary, then:--N(p) = Primary turnsN(s) = Secondary turnsR(2) = Primary resistorR(1) = Secondary resistor--R(2)/R(1) = N(p)/N(s)R(2) = R(1)*(N(p)/N(s))--If arbitrary values are plugged in, you will see that this step up transformer will require 2x the resistance required in the secondary, R(1), to obtain the same current. Thus R(2) will be 1/2 the value of R(1). This is due to the stepped up voltage in the secondary.