Why Is the Current Negative in This Circuit Division Equation?

  • Thread starter Thread starter Miike012
  • Start date Start date
  • Tags Tags
    Current Division
Click For Summary
The current I is negative because it flows in the opposite direction as indicated by the circuit's configuration. The equation I = (-2)(6||3)/(6) reflects this directionality. Kirchhoff's Laws are essential for understanding current flow in circuits, ensuring that the sum of currents entering a junction equals the sum leaving. In this case, the 2mA current from the source flows out of the junction, necessitating the same current to flow through the resistors. Understanding these principles clarifies why the current is negative in this scenario.
Miike012
Messages
1,009
Reaction score
0
Can someone tell me why the current I is negative and not positive?

Im guessing the equation should be:
I = (-2)(6||3)/(6). But why the negative sign?
 

Attachments

  • CC.jpg
    CC.jpg
    5.9 KB · Views: 478
Physics news on Phys.org
Well, the current has to flow in the opposite direction as indicated.

ehild
 
ehild said:
Well, the current has to flow in the opposite direction as indicated.

ehild

Are there any general rules to follow because I'm sure most circuits won't be as obvious
 
There are Kirchhoff's Laws.

The 2mA current of the current source flows out of the top junction, so the same current has to flow in through the resistors. The sum of the currents flowing in is equal to the sum of the outflowing currents according to Kirchhoff's Current Law. So the current flows upward through the 2 kΩ resistor.

ehild
 

Attachments

  • currents.jpg
    currents.jpg
    7.7 KB · Views: 451

Thread 'Magnitude of buoyant force in fluids of different densities'

The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?
View full post »

Similar threads

Current in a circuit without external resistance
  • · Replies 8 ·
Replies
8
Views
2K
Connecting a number of EMF sources in a circle to form a circuit
  • · Replies 9 ·
Replies
9
Views
1K
Using Kirchhoff's law, deduce the value and direction of the current
  • · Replies 6 ·
Replies
6
Views
2K
Understanding the Current Division Rule: A Circuit Diagram Guide
  • · Replies 13 ·
Replies
13
Views
2K
Combined tensions of an RLC series circuit with AC current
  • · Replies 3 ·
Replies
3
Views
989
The Direction and magnitude of current in the inductor
  • · Replies 2 ·
Replies
2
Views
2K
How do I fix the signs in Faraday's Law in RL Circuit?
  • · Replies 5 ·
Replies
5
Views
1K
Using Kirchhoff's laws on this current division problem
  • · Replies 12 ·
Replies
12
Views
2K
Finding the time for an object to start rolling without slipping
  • · Replies 4 ·
Replies
4
Views
2K
Understanding Loop Currents: Why is I3 Negative?
  • · Replies 1 ·
Replies
1
Views
1K