Determining the Direction of Current Flow in Parallel Wires

In summary: Ohm's Law to determine the induced current.In summary, the figure shows two parallel wires carrying current in opposite directions, with a rectangular loop midway between them. As the current decreases, the induced current in the inner loop can be determined using Faraday's Law and Ohm's Law. The direction of the induced current can be determined by using the right hand rule to find the direction of the magnetic field, which is into the page for both wires.
  • #1
jacksonwiley
17
0
Screen Shot 2014-06-12 at 1.36.31 PM.png


1. Homework Statement [/b]
In the figure, two parallel wires carry a current I in opposite directions. A rectangular loop is midway between the wires. The current I is decreasing. The induced current through the resistor R is:
A: Zero
B: from b to a
C: from a to b


Homework Equations




The Attempt at a Solution



i know that in order to find out which way the current is flowing i need to use the right hand rule, but i also need to know if the magnetic field is flowing out or going into the page? I'm not quite sure how i would approach determining that.
 
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  • #2
jacksonwiley said:
View attachment 70561

1. Homework Statement [/b]
In the figure, two parallel wires carry a current I in opposite directions. A rectangular loop is midway between the wires. The current I is decreasing. The induced current through the resistor R is:
A: Zero
B: from b to a
C: from a to b

Homework Equations

The Attempt at a Solution



i know that in order to find out which way the current is flowing i need to use the right hand rule, but i also need to know if the magnetic field is flowing out or going into the page? I'm not quite sure how i would approach determining that.

Welcome to the PF.

For the right wire, your right hand wraps around it from above, with your thumb pointing in the direction of the current. Which way do your fingers go through the inner wire loop?

For the left wire, wrap your right hand around it from above with your thumb pointing in the direction of the current. Which way do your fingers go through the inner wire loop?

So given the situation, which way does the superposition of the two B-fields from the outer wires go through the inner loop? And you are told the B-field is decreasing, so in what direction is the ΔB? What does that tell you about the induced current in the inner loop?
 
  • #3
for the right wire: clockwise
left: counterclockwise

so they go away from each other in the inner loop;
if i remember correctly the direction of B would be out of the page; I'm still a little lost on how to tell which way the current that is induced would flow
 
  • #4
jacksonwiley said:
for the right wire: clockwise
left: counterclockwise

?? The B-field will either be down into the page or up out of the page for the center loop...
 
  • #5
berkeman said:
?? The B-field will either be down into the page or up out of the page for the center loop...

oh i confused the different right hand rules. so they're both into the page. but then which rule do i use to determine the current ?
 
  • #6
jacksonwiley said:
oh i confused the different right hand rules. so they're both into the page. but then which rule do i use to determine the current ?

Correct. Use Faraday's Law to determine the voltage induced in the inner loop by the changing magnetic field...
 

1. How do you determine the direction of current flow in parallel wires?

To determine the direction of current flow in parallel wires, you can use the right-hand rule. Point your right hand in the direction of the current in one wire, then curl your fingers towards the other wire. Your thumb will point in the direction of the current in the second wire.

2. Can the current flow in opposite directions in parallel wires?

Yes, the current can flow in opposite directions in parallel wires. This is known as a "split circuit" and it is often used in electrical circuits to control the flow of electricity.

3. What is the purpose of determining the direction of current flow in parallel wires?

Determining the direction of current flow in parallel wires is important for understanding how electricity flows in a circuit. It can also help with troubleshooting and identifying any potential issues in the circuit.

4. Is there a difference in determining the direction of current flow in AC and DC circuits?

Yes, there is a difference in determining the direction of current flow in AC (alternating current) and DC (direct current) circuits. In AC circuits, the current alternates in direction, while in DC circuits, the current flows in one direction only.

5. Are there any tools or instruments that can help determine the direction of current flow in parallel wires?

Yes, there are tools and instruments that can help determine the direction of current flow in parallel wires. These include multimeters, which can measure the direction and strength of current, and circuit tracers, which can detect the presence and direction of current in a circuit.

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