# Solve 5 Wire Junction Current w/ Conservation of Current

• cse63146
In summary, the conversation discusses the use of Kirchhoff's junction law to determine the current at the 5th wire, which is found to be -9.9 A. The conversation also addresses the need to convert units to meters for length unless otherwise specified.
cse63146

## Homework Statement

The information about the magnitudes of the current density and the diameters for wires 1, 2, 3, and 4 is given in the table. Some of the values are unknown.
Wire Current density (A/mm^2) Diameter (mm) Total Current (A)
1-------- 1.6 -------- 2.0 -------- ?
2 -------- ? -------- 3.0 -------- 2.0
3 -------- 3.0 -------- 1.1 -------- ?
4 -------- 0.8 -------- ? -------- 4.0

What is the current at the 5th wire?

## Homework Equations

I know you need to use the conservation of current, but I'm just not sure what formula to use.

## The Attempt at a Solution

Last edited:
study kirchhoff's junction law...
J = I/pi*r^2 ; pi = 3.14...
Hope this helps... good luck.

would I need to convert the current density and diameter to metres before calculations?

it I5 is going to be-9.84

ravi1611 said:
it I5 is going to be-9.84

Yep, that's the answer I got, just wasnt sure if it was right. Thanks.

Last edited:
yes... always go meters for length unless otherwise specified!
and yess the answer is -9.9

in this case, I didnt convert; I just left it as it

That is because the diameter is in (mm) so is the current density :)

usman27 said:
That is because the diameter is in (mm) so is the current density :)

Ah, good to know. I probably would have done this on the test without noticing. You probably saved me a few marks, Thanks.

## 1. What is meant by "5 wire junction" in this context?

A 5 wire junction refers to a point in an electrical circuit where five wires meet and are connected together. This can be visualized as a junction box or a branching point in a circuit.

## 2. Can you explain the concept of conservation of current?

Conservation of current is a fundamental principle in physics that states that the total amount of electric current flowing into a junction in a circuit must be equal to the total amount of current flowing out of the junction. In other words, the amount of current entering a junction must be equal to the amount of current leaving the junction.

## 3. How is the current calculated in a 5 wire junction using conservation of current?

To calculate the current in a 5 wire junction using conservation of current, you must first determine the total amount of current entering the junction (known as the "incoming current") and the total amount of current leaving the junction (known as the "outgoing current"). The current in the junction can then be calculated by subtracting the outgoing current from the incoming current.

## 4. What factors can affect the current in a 5 wire junction?

The current in a 5 wire junction can be affected by various factors such as the resistance of the wires, the voltage of the circuit, and the number and arrangement of the wires in the junction. Any changes in these factors can alter the amount of current flowing through the junction.

## 5. How is the conservation of current principle applied in practical scenarios?

The conservation of current principle is applied in various practical scenarios, such as in the design and analysis of electrical circuits, troubleshooting faulty circuits, and ensuring the safe and efficient functioning of electrical devices. It is also used in the development of renewable energy sources and the distribution of electricity in power grids.

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