A step-down transforms produces a voltage of 6 V across the secondary coil when

Question

A step-down transforms produces a voltage of 6 V across the secondary coil when the voltage across the primary coil is 120 with a current of 12 mA.   

1) What is the current from the secondary coil?

Isec =   

2) What is electrical power into the primary coil?

Eprimary =

3) What is electrical power out of the secondary coil?

Esecondary =

4) Now assume the transformer is flipped around so that the 120 V is placed on to what was the secondary coils. What is now the voltage across what was originally the primary coils?

Vflipped =

Explanation / Answer

In a transforner Ns/Np = Vs/Vp = Ip/Is

where NS ans Np are seconda dr and primary tunrs

Vs and Vp are secondary and primary volatges

Is and Ip are secondary and prianry currents

also in ideal transformer output P = input P

part A:

Is = Ip * Vp/Vs

Is = 12 * 120/6

is = 240 mA

--------------------------------------

part2:

Primary Power P = Vp Ip

Primary Power = 120 * 12e-3 = 1.44 Watts

------------------------------------

part 3:

Seconday Power = VsIs

Ps = 240 e -3 * 6 = 1.44 Watts

---------------------------------------------

part 4:

Vp/vs = Is/Ip

Vp = 120 * 240/120

Vp = 240 Volts (is the Vflipped)

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