Trade-offs revisited

In circuits

Imagine two circuits. In both, the goal is to get the same power in the pathway.

Make choices about the current and potential difference to achieve that goal.

Of course, you could choose identical currents and potential differences in both circuits. But there are many other choices you could make: many trade-offs between a choice of current and choice of potential difference to achieve the goal.

In all pathways

That's true of all four pathways: you've seen that pairs of physical quantities set the power.

power = current × voltage

power = velocity × force

power = photonsecond × energyphoton

power = particlesecond × energyparticle

You've probably also noticed that the area of the box sets the value of the power: that's because of the multiplication.