Calculating current

Discussion in 'Homework Help' started by hannah, Jan 30, 2008.

  1. hannah

    Thread Starter New Member

    Jan 29, 2008
    1
    0
    I dont get this question , can someone show me how to work it out. casue my teacher did not explain it very well in class!!

    In a motor vehicle, a relay is used to switch the 12 V , 60 W headlight on and off.

    The resistance of the relay coil is 150 ohms . Calculate the current in the relay coil when it is connected to a 12 V supply.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    I = E/R - Ohm's law.
     
  3. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    beenthere is correct. Here is a link to the AAC ebook section pertaining to Ohm's Law. Reviewing the material and working through the examples shown should help clear up the topic for you.

    hgmjr
     
  4. chesart1

    Senior Member

    Jan 23, 2006
    269
    1
    Note that the problem asks for the current through the relay coil. Not through the headlight.

    You need to look at the circuit. If a circuit was not provided, then you can assume that the relay coil is not connected to the headlight. The relay contacts connect the headlight to 12 volts. Therefore the information about the headlight is not needed to solve the problem.
     
  5. JoeJester

    AAC Fanatic!

    Apr 26, 2005
    3,373
    1,159
    That is all you need to know. Forget the headlight.
     
  6. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Is this one of those questions where you are provided more information than you actually need? These always get the people that don't understand the problem and are used to just pluggin in equations :p

    Steve
     
Loading...