Circuits Problem (Physics)

posted by .

h t t p ://img266.imageshack.us/my.php?image=circuit2ru6.png

Given the circuit above:
a) Solve for unknown currents.
b) What is the potential difference between points a and b?
c) If both batteries start with 20 A*h of charge, how long does it take the first of the batteries to run out? Which battery is it (left or right)?
d) If both 12V batteries are replaced by batteries of identical voltage, what is the smallest voltage which will result in integer currents throughout the circuit?

  • Circuits Problem (Physics) -

    Sorry, can not open your image :(

  • Circuits Problem (Physics) -

    hi,
    i put spaces between the "h t t p :" because it wouldnt let me post it otherwise. if you delete the spaces it should load (i hope!).

  • Circuits Problem (Physics) -

    I call the current coming out the top of the left battery i1
    I call the current coming out the top of the right battery i2
    Then the current headed down from a to b is (i1+i2) (Kirkhoff)
    In the left loop
    12 = 4 i1 + 6(i1+i2)
    In the right loop
    12 = 3 i2 + 6(i1+i2)
    so
    12 = 10 i1 + 6 i2
    12 = 6 i1 + 9 i2
    solve those two. I will multiply the first by three and the second by 2
    36 = 30 i1 + 18 i2
    24 = 12 i1 + 18 i2
    subtract
    12 = 18 i1
    i1 = 2/3
    then i2
    12 = 10(2/3) + 6 i2
    12 = 20/3 + 6 i2
    36 = 20 + 18 i2
    16 = 18 i2
    i2 = 8/9

  • Circuits Problem (Physics) -

    b)
    i1+i2 = 2/3 + 8/9 = 14/9
    times the resistance which is 6 = 28/3 volts a above b

  • Circuits Problem (Physics) -

    2/3 = 6/9 = i1
    8/9 = i2
    so i2>i1 so the one on the right will run out first
    (8/9) t = 20 amp hr
    t = 9*20/8 = 9*5/2 = 22.5 hr

  • Circuits Problem (Physics) -

    at present i1 = 6/9 and i2 = 8/9
    clearly if I multiply the voltages by 9 I will get 6 amps and 8 amps
    then if I divide both voltages by two I will get 3 amps and 4 amps
    so multiply the voltage by 9/2
    (9/2)12 = 54 volts

  • Circuits Problem (Physics) -

    omg! thankss!!

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Physics

    An electric force moves a charge of +1.40 x 10^-4 C from point A to point B and performs 4.70 x 10^-3 J of work on the charge. (a) What is the difference (EPEA - EPEB) between the electric potential energies of the charge at the two …
  2. Physics-Ohms Law

    Will you check my answers please? A volt is a unit of current and an amprere is a unit of current. It is common to call electric potential difference- voltage A current of 1 ampere is a flow of charge at the rate of 1 coulomb per second.
  3. Short Circuit Problem (Physics)

    Thanks so much for all your help damon! I think this is my last one: h t t p ://img408.imageshack.us/my.php?
  4. [Physics] super hard/long circuit problem

    I have this last one which is really long/hard. It's so long that I just decided to scan the whole problem. So here it is... and thanks everyone for the help so far! h t t p ://img201.imageshack.us/my.php?
  5. Circuit Problem- Physics

    I am trying to do these 2 problems. I'm starting out with the RC Circuit (2nd one): h t t p ://img201.imageshack.us/my.php?
  6. Continued physics problem from before (way down)

    Posted by Eileen on Sunday, April 13, 2008 at 10:05am. I am trying to do these 2 problems. I'm starting out with the RC Circuit (2nd one): h t t p ://img201.imageshack.us/my.php?
  7. physics electricity

    An electric force moves a charge of +1.65 multiplied by 10-4 C from point A to point B and performs 6.40 multiplied by 10-3 J of work on the charge. (a) What is the difference (EPEA - EPEB) between the electric potential energies of …
  8. Physics

    Thank you for answering my previous questions! I have another one now in regards to the following question... An unknown potential difference exists between the inner and outer surfaces of the membrane of a cell. The inner surface …
  9. Physics

    A circuit consists of a 10 ohm resistor in series with 3 identical batteries each with an emf = 1.0V and internal resistance of 5 ohms. a) find potential difference between the terminals b) potential difference across the 10 ohm resistor …
  10. Physics- Circuits Current & Voltage Problem

    Please find this question onto y a h o o s e a r c h e n g i n e b y c o p y & p a s t e. Determine... (a) the current in each resistor (Indicate the direction of the current flow through each resistor through the sign of your answer. …

More Similar Questions