How does power change with voltage?

1 Answer

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 #