This simulation shows the effects of an ideal transformer in an AC circuit. The driving emf and the resistance of the primary (p-subscript) and secondary (s-subscript) sides of the circuit can be adjusted using the blue sliders. The number of turns of wire on each side of the transformer can be adjusted using the green sliders. Observe how the current and power dissipated (shown as a horizontal bar chart under the circuit) changes.

Typically, power dissipated in the secondary side of the circuit is useful (for example, it could be used to power a speaker), while power dissipated in the secondary side is wasted. What combination of parameters delivers the maximum amount of power to the secondary, both as an absolute number, and as a percentage of the total power?

Adjust the two resistances to different values. What turns ratio () will maximize the power delivered to the secondary side of the circuit? Check that it's the ratio that matters by doubling both and .

Set the turns ratio to 1 and to 10 ohms. What value of will maximize the power delivered to the secondary side of the circuit?