# Electric Potential: Calculating Energy & Power

• alligrass
In summary, to find the energy wasted when 35 C of charge flow through a 120 V toaster in 5.0 S, we can use the formula work=qv and calculate 35(120)=4200 J. To find power, we can use the formula power=work/time and calculate 4200/5=840 J/s. We can also use the formula P=IV and calculate 7(120)=840 J/s. Both methods give the same result of 840 J/s.
alligrass

## Homework Statement

how much energy is wasted when 35 C of charge flow through a 120 V toaster in 5.0 S?
how much power?

## Homework Equations

work=qv i think...

power= work /time

## The Attempt at a Solution

i thought to find energy wasted i would find the work used. (?yes?)

so i guess that would be 35(120) whihc is 4200 J

so then do i power = 4200/5=840

is this correct?

well P = IV

and they give you the time...so you know the units of Power = (Joules/second), so given the time you can find the joules wasted...

both problems solved with one equation!

:D

wait i didnt really understand what u just said.
did i do this right or is it wrong?

no recheck your work and look at the formula I gave you and the units of power, energy is in JOULES, and power is in Watts or Joules/second...it should be straightforward from there

well a watt = J/sec
so i got energy in joules correct right??

then those Joules per 5 sec gives u 840 J/ a sec

ok another formula that will help is to know that I (current) is equal to (change in Q- the charge)/ (change in time - seconds), both of these informations are given in the problem...

once you find I...you can solve for P = IV, using the information given in the problem...

oh and I forget to mention that the change in potential difference (V) is equal to the potential-energy change per unit charge in moving across the toaster...so U = Vq...you know volts and know q so you can find the energy lost.

so isn't i=7
and then 7(120)=840...

ddint i do that in the proble, above?

ohh..lol my bad, yes your work is correct, sorry for the explanation again above...wasn't thinking so simply...

## What is electric potential?

Electric potential is a measure of the potential energy per unit charge at a given point in an electric field.

## How do you calculate electric potential?

Electric potential can be calculated using the formula V = kQ/r, where V is the potential, k is the Coulomb constant, Q is the charge, and r is the distance from the charge.

## What is the unit of electric potential?

The unit of electric potential is volts (V), which represents the amount of potential energy per unit charge.

## Can electric potential have a negative value?

Yes, electric potential can have a negative value. This indicates that the potential energy is lower at that point compared to a reference point.

## How is electric potential related to energy and power?

Electric potential is directly related to energy and power. Energy is equal to the product of electric potential and charge, while power is equal to the product of electric potential and current.

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