Electric Potential: Calculating Energy & Power

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SUMMARY

The discussion focuses on calculating energy and power in an electrical circuit involving a toaster. The energy wasted when 35 C of charge flows through a 120 V toaster in 5.0 seconds is determined to be 4200 Joules. The power is calculated using the formula P = work/time, resulting in 840 Watts. The participants confirm the correctness of these calculations and clarify the relationship between current, voltage, and energy in the context of electrical circuits.

PREREQUISITES
  • Understanding of electric charge (Coulombs)
  • Familiarity with voltage (Volts)
  • Knowledge of power calculations (Watts)
  • Basic principles of energy (Joules)
NEXT STEPS
  • Study the relationship between current, voltage, and resistance using Ohm's Law
  • Learn about energy conservation in electrical systems
  • Explore the concept of power factor in AC circuits
  • Investigate the efficiency of electrical appliances
USEFUL FOR

Students studying electrical engineering, physics enthusiasts, and anyone interested in understanding energy consumption and power calculations in electrical devices.

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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?
 
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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?
 
  • #10
ohh..lol my bad, yes your work is correct, sorry for the explanation again above...wasn't thinking so simply...
 

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