Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: How much energy does the kettle transfer?

  1. Sep 15, 2004 #1
    I know that Tom wants us to at least have one go at answering the question ourselves but Ihave been haunted by this question for almost a week now and I don't feel ay closer to answering it.

    I have been given the electron charge which is 1.6*10-19 C and I have been given the question "An electric kettle is labelled "230V, 2.3kW". It takes 2.5 minutes to boil some water.
    How much energy does the kettle transfer?

    How am I meant to answer this questin if I am not given some sort of other energy to compare the electric enegy to?
    Please help

    Chris
     
    Last edited: Sep 15, 2004
  2. jcsd
  3. Sep 15, 2004 #2
    ps: the italic -19 is meant to be a small -19 above to the right of the 10.
     
  4. Sep 15, 2004 #3

    Chi Meson

    User Avatar
    Science Advisor
    Homework Helper

    You have been given voltage and power. Power is the rate of energy transfer(P = E/t) . So "watts" = "joules"/"seconds" therefore, E = Pt "joules" = "watts" x "seconds" . You don't need the charge of the electron nor the voltage for this problem.
     
  5. Sep 15, 2004 #4
    Thankyou :biggrin:
    It never seemd to occur to me that power is the energy transfer but now it makes so much sense I feel quite stupid...lol! :rofl:
     
    Last edited: Sep 15, 2004
  6. Sep 15, 2004 #5

    Chi Meson

    User Avatar
    Science Advisor
    Homework Helper

    That's what Physics is all about!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook