# How Do You Calculate Diode Current in a Circuit with Second Approximation?

• tgitgi
In summary, the conversation is about a circuit with a voltage input of 12V, resistor 1 of 2k ohms, and resistor 2 of 4k ohms connected to a diode and a load resistance of 1k ohm. The problem is to find the load voltage, load current, load power, diode voltage, diode power, and diode current. The conversation also mentions using the second approximation. The solution involves finding the Thevenin voltage and resistance, and using the relationship between load current and diode current. The diode current is assumed to be the same as the load current because the diode and load resistor are in series.
tgitgi
1. So I have a voltage input of 12V, resistor 1 of 2k ohms, and resistor 2 of 4k ohms. These are connected to a diode and a load resistance of 1k ohm and load. I am instructed to use second approximation

2. The problem wants me to find load voltage, load current, load power, diode voltage, diode power, and diode current. I haven't had an issue with any except diode current.
3. I started by finding the thevenin voltage of 8V and thevanin resistance of 1.3k ohms
I found load current by subtracting VTH and 0.7 and dividing by the sum of RTH and RL. (~3.17 mA)
I found load voltage by multiplying IL and RL (~3.17 V)
Load power by IL * VL (~10 mW)
Diode voltage is 0.7V because of second approx.
Now, how do I find the diode current? My book seems to assume diode current is the same as load current. Why is that?

Hi tgitgi, Welcome to Physics Forums.

Your problem statement is not clear for everyone. Note that we don't all have the benefit of being in the same class with you or having the same course materials to reference. So, Can you please:

1. Provide a better description of the circuit or (even better) post a circuit diagram?
2. Define what "second approximation" means.

(Note that if the diode and load resistor are series-connected then they must share the same current)

Last edited:
tgitgi and LvW

## 1. What is the current of a diode?

The current of a diode is the flow of electric charge through the diode. It is measured in units of amperes (A).

## 2. How do you find the current of a diode?

To find the current of a diode, you can use Ohm's Law (I = V/R) where I is the current, V is the voltage across the diode, and R is the resistance of the diode. You can also use a multimeter to directly measure the current.

## 3. What affects the current of a diode?

The current of a diode can be affected by the voltage applied across it, the temperature of the diode, and the amount of light hitting the diode (in the case of a photodiode).

## 4. How does the current of a diode change with voltage?

The current of a diode follows an exponential relationship with voltage. As the voltage increases, the current also increases, but at a decreasing rate. This is due to the forward voltage drop of the diode.

## 5. Why is it important to find the current of a diode?

Finding the current of a diode is important for understanding the behavior of the diode in a circuit. It can also help in troubleshooting and determining the correct operating conditions for the diode.

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