Results 1 to 4 of 4

Thread: [HELP WANTED] Physics: Electricity

  1. #1
    Charlotte's Avatar
    Joined
    Dec 2011
    Posts
    60
    Userbars
    1
    Thanks
    2
    Thanked
    2/1
    DL/UL
    18/0
    Mentioned
    24 times
    Time Online
    1h 17m
    Avg. Time Online
    N/A

    Exclamation [HELP WANTED] Physics: Electricity

    A 120-V circuit contains a 20.0-Ω resistor and a 40.0-Ω resistor connected in parallel.
    a) What is the current through the 40.0-Ω resistor?
    b) What is the total current in the circuit?


    Any help at all is appreciated!

  2. #2
    bamag's Avatar
    Joined
    Dec 2011
    Posts
    656
    Userbars
    3
    Thanks
    40
    Thanked
    146/110
    DL/UL
    34/0
    Mentioned
    50 times
    Time Online
    N/A
    Avg. Time Online
    N/A
    Just wondering, what level of physics is this?
    I think you can use Ohm's Law.
    I=V((1/R1)+(1/R2)) where I is current, V is voltage, and R is resistance.
    I haven't done much on electricity so I'm not too sure.

  3. #3
    Ryan~'s Avatar
    Joined
    Jan 2012
    Posts
    123
    Userbars
    5
    Thanks
    1,380
    Thanked
    1,424/827
    DL/UL
    103/4
    Mentioned
    640 times
    Time Online
    15d 12h 13m
    Avg. Time Online
    5m
    Based on what you provided, you can conclude that the total current is 9 Ohms.

    120(1/20+1/40)
    120(3/40)
    9

  4. #4
    holyzac's Avatar
    Joined
    Jan 2012
    Posts
    172
    Userbars
    2
    Thanks
    6
    Thanked
    41/21
    DL/UL
    5/0
    Mentioned
    5 times
    Time Online
    20m
    Avg. Time Online
    N/A
    Ohm is the SI unit for Resistance and not Current which is A for amperes

    The formula in Ohm's law I = V/R is applied to each resistor in a parallel circuit to get the current following at that section.
    The total current in a parallel circuit is the total current from each section of the parallel circuit.

    Therefore,
    a)What is the current through the 40.0-Ω resistor?
    120V/40Ω= 3A

    b)What is the total current in the circuit?
    Current at 20Ω resistor - 120V/20Ω= 6A
    Total current in the circuit - 6A+3A= 9A

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •