Magnitude and direction of the current in conductor

AI Thread Summary
The discussion revolves around confirming the correctness of answers related to electric current in conductors and circuit analysis. The user provided specific scenarios involving junction P, including calculations for current magnitude and direction, and sought validation for their choices. They explained their reasoning for selecting certain answers based on the behavior of currents at junctions and the application of Ohm's law. The user also included detailed calculations for a complex circuit, asserting that their results appear accurate. Overall, the thread emphasizes the importance of verifying circuit analysis and understanding current flow in electrical systems.
bap902
Messages
25
Reaction score
0
I have a few questions on three circuits problems that I have already solved. I explained how I arrived at my answers and included diagrams. I would appreciate any help in confirming that my answers are correct. Thank you!

1. The diagram below shows electric currents in conductors that meet at junction P.

http://www.stmary.ws/physics/home/marys_java/regents/Januar14.gif

What are the magnitude and direction of the current in conductor PQ? (1) 9 A toward P (2) 9 A toward Q (3) 5 A toward P (4) 5 A toward Q

I chose choice #4, 5 A toward Q because when 3 and 4 are added you get 7. But, because of the 2 moving in the opposite direction, it takes away from the overall total of 7 leaving you with 5.

2. Which diagram below correctly shows currents traveling near junction P in an electric circuit?

http://www.stmary.ws/physics/home/marys_java/regents/June0114.gif

(1) 1 (2) 2 (3) 3 (4) 4

I chose choice #4 because that is the only one where all the arrows correctly show that that the current is traveling near junction P. The arrows indicate the direction of the current toward the junction.

3. Determine the following using the figure below:
http://img509.imageshack.us/img509/8186/circuitoh0.png

R(total)= 25 ohms
I(total)= 4 amps
V(x-->y)= 20 volts
V(y-->z)= 20 volts
V(x-->z)= 40 volts
I(5 ohm resistor)= 1.3 amps
Power(10 ohm resistor - not the parallel ones)= 160 watts
Power (15 ohm parallel resistors)=26.7 watts

I included my answers as well as how I broke down the complex circuit into a simple circuit so I could arrive at those answers using the V=IR formula and working backwards.
 
Last edited by a moderator:
Physics news on Phys.org
Anyone?
 
Bump.
 
The answers looks correct to me!
 
Thread 'Variable mass system : water sprayed into a moving container'
Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
I was thinking using 2 purple mattress samples, and taping them together, I do want other ideas though, the main guidelines are; Must have a volume LESS than 1600 cubic centimeters, and CAN'T exceed 25 cm in ANY direction. Must be LESS than 1 kg. NO parachutes. NO glue or Tape can touch the egg. MUST be able to take egg out in less than 1 minute. Grade A large eggs will be used.
Back
Top