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Questions and Answers
What happens to the depletion region as the voltage in forward bias increases?
What happens to the depletion region as the voltage in forward bias increases?
What is the approximate cut-in voltage for a silicon diode?
What is the approximate cut-in voltage for a silicon diode?
Which statement best describes the current in reverse bias?
Which statement best describes the current in reverse bias?
How does the resistance of a pn junction change in forward bias?
How does the resistance of a pn junction change in forward bias?
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What does a circuit symbol for a pn junction represent?
What does a circuit symbol for a pn junction represent?
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Which term describes the behavior of a pn junction in relation to Ohm's law?
Which term describes the behavior of a pn junction in relation to Ohm's law?
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Study Notes
- The behavior of a pn junction can be summarized in a graph of voltage versus current.
- In forward bias, when the positive terminal is connected to the p-type and the negative terminal is connected to the n-type, current flows from p to n.
- Initially, with a small voltage, the current is not significant due to the depletion region. As the voltage increases, the depletion region becomes smaller and the current grows. After a certain point, called the cut-in voltage, the depletion region vanishes and the current increases rapidly.
- The cut-in voltage for a silicon diode is approximately 0.7 volts.
- In reverse bias, when the positive terminal is connected to the n-type and the negative terminal is connected to the p-type, a very tiny current flows in the opposite direction from n to p. The current remains near zero and almost constant.
- The graph of reverse bias shows a constant near-zero current.
- The graph of forward bias shows a low current until the cut-in voltage, after which the current increases dramatically.
- A pn junction is a non-ohmic device, meaning Ohm's law does not apply to it.
- In forward bias, the pn junction has low resistance, while in reverse bias, it has high resistance to current.
- The circuit symbol for a pn junction represents the direction of conduction, with an arrow indicating conduction from p to n.
- A pn junction is also known as a pn diode, semiconductor diode, or junction diode.
- The word "diode" refers to a device with two terminals (p and n) that allows a path for charges to flow in one direction.
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Description
Explore the behavior and characteristics of a pn junction through a voltage versus current graph. Learn about forward bias, reverse bias, cut-in voltage, resistance, and more.
