1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: Alternating current

  1. Feb 5, 2008 #1
    1. The problem statement, all variables and given/known data
    A light bulb is connected to a 120.0-V wall socket. The current in the bulb depends on the time t according to the relation I = (0.669 A) sin [(491 Hz)t].

    What is the frequency of the alternating current?

    2. Relevant equations
    How do I use the given value for I?? (since it includes time, t)

    3. The attempt at a solution
    I know that V=Vo * sin2pi * freq * time
  2. jcsd
  3. Feb 5, 2008 #2


    User Avatar
    Homework Helper

    The only relevant equation you should be using is:


    Suppose I have the equation sin(pi*x), can you tell me what the period of this function is? Can you tell me the frequency? Draw it out. Now if I tell you I have the equation sin(491*x), can you tell me the same information?

    You will notice a pattern such as: sin(k*x) -> sin(2*pi*f*x) in terms of frequency.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook