A step-up transformer has 500 turns on its primary and 1000 turns on its secondary. When the primary is connected to 100 V and the secondary is connected to a floodlight that draws 4 A, what is the power output?

Vo = 1000/500 * 100 = 200 Volts.

Po = Vo*Io = 200 * 4 = 800 Watts.

To find the power output of the step-up transformer, we need to use the formula:

Power (P) = Voltage (V) x Current (I).

Given information:
Primary turns (Np) = 500
Secondary turns (Ns) = 1000
Primary voltage (Vp) = 100 V
Secondary current (Is) = 4 A

First, we need to determine the secondary voltage (Vs) using the turns ratio:

Turns ratio (K) = Ns/Np = 1000/500 = 2.

Since the transformer is a step-up transformer, the secondary voltage will be greater than the primary voltage:

Vs = K * Vp = 2 * 100 V = 200 V.

Now that we have the secondary voltage, we can find the power output:

Power output (Ps) = Vs x Is = 200 V x 4 A = 800 VA (Volt-amperes).

The power output is 800 VA.