# Comparing Resistance in PN Diodes

• Eman 55
In summary, the circuit with the largest resistance to the current is the one in figure C, where the pn diode is reverse-biased.

## Homework Statement

I came across a question asking " which one of these circuits has the largest resistance to the current?

## The Attempt at a Solution

* In A the positive terminal of the battery is connected to the p-type region and the negative one to the n-type region (forward bias) so, the field due to the battery is opposite to the internal field in the transition region and therefore, it weakens it. The resistence will be small and the current will flow.
* C is the opposite case of A since it shows that the pn diode is connected in reverse direction. The resistance will be large and the current is almost zero.
But I'm not sure about the B case.

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Eman 55 said:

## Homework Statement

I came across a question asking " which one of these circuits has the largest resistance to the current?
View attachment 227031

## The Attempt at a Solution

* In A the positive terminal of the battery is connected to the p-type region and the negative one to the n-type region (forward bias) so, the field due to the battery is opposite to the internal field in the transition region and therefore, it weakens it. The resistence will be small and the current will flow.
* C is the opposite case of A since it shows that the pn diode is connected in reverse direction. The resistance will be large and the current is almost zero.
But I'm not sure about the B case.
B is a "resistor " with positive charge carriers. It can be a piece of p-type semiconductor.

Eman 55 said:

## Homework Statement

I came across a question asking " which one of these circuits has the largest resistance to the current?
View attachment 227031

## The Attempt at a Solution

* In A the positive terminal of the battery is connected to the p-type region and the negative one to the n-type region (forward bias) so, the field due to the battery is opposite to the internal field in the transition region and therefore, it weakens it. The resistence will be small and the current will flow.
* C is the opposite case of A since it shows that the pn diode is connected in reverse direction. The resistance will be large and the current is almost zero.
But I'm not sure about the B case.
You are right in your analysis. The diode in figure C is reverse-biased and will offer the largest resistance to the current (assuming that the applied voltage is low enough to prevent reverse-breakdown).
Figure B shows a p-type semiconductor. Its conductivity will depend on the amount of doping and temperature.

Eman 55

## 1. How do you compare resistance in PN diodes?

To compare resistance in PN diodes, you can use a multimeter in resistance mode to measure the resistance of each diode. The higher the resistance value, the less current the diode will allow to pass through.

## 2. What is the purpose of comparing resistance in PN diodes?

Comparing resistance in PN diodes helps in understanding the electrical characteristics of the diodes and identifying their functionality. It also allows for troubleshooting and selecting the appropriate diodes for specific circuits.

## 3. Can you compare the resistance of different types of PN diodes?

Yes, you can compare the resistance of different types of PN diodes, such as silicon or germanium diodes. However, the resistance values may vary due to differences in material and construction of the diodes.

## 4. How does temperature affect the resistance of PN diodes?

The resistance of PN diodes decreases as temperature increases. This is due to the increase in thermal energy, which allows more electrons to overcome the energy barrier and flow through the diode.

## 5. What factors can affect the resistance of PN diodes?

The resistance of PN diodes can be affected by temperature, light, and the amount of doping (introducing impurities) in the diode's semiconductor material. The diode's physical structure, such as size and shape, can also impact its resistance.