Question

How does power change with voltage?

Answer 1

Power `P` is related to voltage `V` and current `I` as:

`P = V * I`

So the power will increase proportionally with the voltage if I is constant.

This is because power is defined as energy consumed per second as stated in the equation:

`P = E/t` where E is energy and t is time.

Voltage is defined as the amount of energy per charge:

`V = E / Q` where Q is the amount of charge in Coulumbs and E is the amount of energy in Joules.

Current is defined as the the flow of charge per unit time:

`I = Q/t`

So when we multiply `V*I` we get:

`V * I = E/Q * Q/t = E/t = P`

We can also find Power from voltage and resistance because we know from Ohm's law that:

`I = V/R` and so electric power can be related to voltage and resistance as:

`P = V*I = V*V/R = V^2/R`