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Series and Parallel Resistor

  1. Dec 20, 2007 #1
    hi! I need some assistance regarding my assignment. hope there's anyone who could help me out. the questions are:

    1.a. a 12 ohms resistor is connected in parallel with a series combination of resistors of 8 ohms and 16 ohms. if voltage drop across the 8 ohms resistor, is 48 volts. Determine the total impressed voltage and total current. Vt=? It=?

    1.b. Relevant equations
    V = IR; I=V/R

    1.c. The attempt at a solution
    so... first i have to get the total resistance to get the total current and voltage right? (Please correct me if i'm wrong. thanks! :D)

    R12 = 8ohms + 16ohms = 24ohms

    1/RT = 1/R12 + 1/R3
    1/RT = 1/24 + 1/12ohms
    1/RT = 1/8 ohms

    Rt = 8 ohms

    here's the part where i'm totally confused
    It = Vt/Rt
    It = 48Volts / 8 ohms
    It = 6 A

    Vt = 48? (i really dont know how to solve for the total voltage)

    2.a. 2 resistors 1.95ohms and 0.05ohms are connected in parallel and takes a total current of 50V. What is the current in each resistor?

    2.b. Relevant equations
    I1 = It

    I1 = V1/R1

    2.c. The attempt at a solution

    I1 = 50V / 1.95ohms
    I1 = 25.64 A

    I2 = 50V / 0.05ohms
    I2 = 1000 A
  2. jcsd
  3. Dec 20, 2007 #2
    voltage is the same for all when in parallel
    current is the same for all when in series.
    (ie: when you use the meter to emasure voltage, you put the probe across 2 points hence the probe is in parallel with component, but when you measure current you cannot do the same, need to make it part of the circuit)

    for first part, find voltage drop across 8 and 16, then voltage across both of that is same as 12ohm (ie: if 48v across 8 ohm, and since 8 ohm in series with 16 and they share same current, how much is voltage across 16ohm, then what is the total voltage across 8series16, this is your answer)
    for 2nd, you need to find the equivalent resistance, then find current

    for 2nd, how does it take total current 50V? you mean 50A? do a current divider
    least resistance means more current flow in that direction
    Last edited: Dec 20, 2007
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