Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    0
    ReputationRep:
    A has a value of 2 ohms B a value of 4 ohms, the cell is 2 volts and 1 ohm

    I need to calculate the current in A and B and the p.d. between the terminals of the cell.

    For the Current in A i did I=v/R for the cell so 2/1 = 2 and we know ina parallel the voltage stays the same so its going to be 2/2 = 1 amp, but in the answers they get 0.47A, similalry with B

    C im not too sure about
    Attached Images
     
    Offline

    0
    ReputationRep:
    Hello Hazbaz

    in your fig, and taking C to be 2 ohm, we have a circuit something like this.


    (joints the other end/earth)------[cell]------[A]------[B // C]------(joints the previous end/earth)


    = ()------[Vcell ideal+ Cell Resistance]------[A]------[B // C]------()

    Now, total resistance [TR] of the system = [CR] + [A] +[B//C] = [CR] + [A] +{B*C/(B+C)}

    = 1+2+[4//2] = 3 + (8/6) = 26/6

    cell potential / total resistance gives the total current or the current flowing through [A]. = 0.46 A


    from this you should be able to calculate current through B.

    potential across B = potential across C

    Ib*Rb = Ic*Rc

    Ib +Ic = 0.46

    You should be able to work out this to find Ib

    Now the potential across [TR] =ideal cell voltage = 2Volts.

    [TR] = cell resistance (1ohm) + external effective resistance (20/6)ohms ([A]+[B // C])

    of which the potential across 1 ohm is lost within the cell, and the potential across {[TR]-1} is avaliable cell voltage.(potential across the cell)
    or simply, a current of 0.46A through 1ohm resistance drops/develops 0.46V. The remaining is the avaliable cell voltage.

    I hope now you can work out own your own.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    What newspaper do you read/prefer?
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.