# Need to find two currents in this circuit

• Engineering
• opticaltempest
In summary, the conversation discusses trying to find the currents I_D1 and I_D2 labeled in the picture and the difficulty in obtaining their correct values using KCL or KVL. The circuit is seemingly simple but has proven to be challenging. A possible solution is to use KCL at the node to the right of the I_D1 arrow, which results in the equation -I_{D1}+I_{D2}-I_{6V}=0. Another method is to use mesh analysis, which would result in two equations for the circuit. The simplest solution is the one used in the conversation, which involves using KCL at the designated node.
opticaltempest
I am trying to find the currents I_D1 and I_D2 labeled in the picture by the arrows. I am stumped on how to obtain the correct values for the currents. I am having trouble using either KCL or KVL. This circuit seems simple but has me stumped.

http://img127.imageshack.us/img127/8600/circuitvz9.jpg

If I write KCL at the node to the right of the I_D1 arrow I get

$$-I_{D1}+I_{D2}-I_{6V}=0 \implies$$

$$I_{D1}=I_{D2}-I_{6V}.$$

$$I_{6V}=\frac{6V}{43k\Omega}=140\mu A$$

$$I_{D2}=\frac{9V}{22k\Omega}=409\mu A$$

Is there an easier or different way to do this problem, perhaps using KVL instead of writing a KCL equation at the node I used?

Thanks

Last edited by a moderator:
Yes you can also do it via mesh analysis. You would have 2 equations here.

opticaltempest said:
I am trying to find the currents I_D1 and I_D2 labeled in the picture by the arrows. I am stumped on how to obtain the correct values for the currents. I am having trouble using either KCL or KVL. This circuit seems simple but has me stumped.

http://img127.imageshack.us/img127/8600/circuitvz9.jpg

If I write KCL at the node to the right of the I_D1 arrow I get

$$-I_{D1}+I_{D2}-I_{6V}=0 \implies$$

$$I_{D1}=I_{D2}-I_{6V}.$$

$$I_{6V}=\frac{6V}{43k\Omega}=140\mu A$$

$$I_{D2}=\frac{9V}{22k\Omega}=409\mu A$$

Is there an easier or different way to do this problem, perhaps using KVL instead of writing a KCL equation at the node I used?

Thanks

The simplest way to solve the circuit is the one you used.

Last edited by a moderator:
Quick solution:

Hey this is a simple mesh anaylisis problem.. I've included a solution. I hope it helps. Cheers

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## What is a circuit?

A circuit is a closed loop through which an electric current can flow. It typically includes a power source, such as a battery, and various components, such as resistors, capacitors, and switches, that are connected by conductive wires or paths.

## How do you find currents in a circuit?

To find the currents in a circuit, you can use Ohm's Law, which states that the current (I) is equal to the voltage (V) divided by the resistance (R). You can also use Kirchhoff's Laws, which describe the conservation of charge and energy in a circuit, to solve for currents.

## What are the units of measurement for current?

The SI unit for current is the ampere (A), which is defined as the flow of one coulomb of charge per second. In practical applications, current is often measured in milliamperes (mA) or microamperes (μA).

## What factors can affect the currents in a circuit?

The currents in a circuit can be affected by various factors such as the voltage of the power source, the resistance of the components in the circuit, and the type of connections between components (i.e. series or parallel). Changes in any of these factors can cause the currents to change.

## Why is it important to find currents in a circuit?

Knowing the currents in a circuit is important for understanding how the circuit functions and for troubleshooting any issues that may arise. It also helps in designing and optimizing circuits for specific purposes, such as controlling the flow of electricity in electronic devices or powering various electrical systems.

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