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An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, then
- a)the effective base width increases and common – emitter current gain increases
- b)the effective base width increases and common – emitter current gain decreases
- c)the effective base width decreases and common – emitter current gain increases
- d)the effective base width decreases and common – emitter current gain decreases
Correct answer is option 'C'. Can you explain this answer?
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An npn bipolar junction transistor (BJT) is operating in the active re...
If the reverse bias voltage across the base collector junction is increased, then their effective base width will decrease and collector current will increase, therefore their common-emitter current gain increases.
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An npn bipolar junction transistor (BJT) is operating in the active re...
Explanation:
In an npn bipolar junction transistor (BJT), the reverse bias across the base-collector junction is an important parameter that affects the device's operation. Let's discuss the effect of increasing the reverse bias on the effective base width and the common emitter current gain.
Effect on Effective Base Width:
When the reverse bias across the base-collector junction is increased, it causes the depletion region at the junction to widen. This widening of the depletion region effectively reduces the width of the base region available for the flow of majority charge carriers (electrons in the case of an npn transistor). Therefore, the effective base width decreases.
Effect on Common Emitter Current Gain:
The common emitter current gain (β) of a BJT is defined as the ratio of the collector current (IC) to the base current (IB), i.e., β = IC/IB. It represents the amplification capability of the transistor.
When the reverse bias across the base-collector junction is increased, the depletion region widens, as mentioned earlier. This widening of the depletion region results in a larger electric field across the base region. This electric field accelerates the minority charge carriers (holes in the case of an npn transistor) away from the base-collector junction and towards the collector.
As a result of this increased acceleration, a larger number of minority charge carriers are collected by the collector, resulting in an increased collector current (IC). Since the common emitter current gain is defined as the ratio of IC to IB, an increase in IC without a corresponding change in IB will lead to an increase in β.
Therefore, when the reverse bias across the base-collector junction is increased, the effective base width decreases, and the common emitter current gain increases. So, the correct answer is option 'C'.
Summary:
- Increasing the reverse bias across the base-collector junction of an npn BJT decreases the effective base width.
- Increasing the reverse bias also increases the common emitter current gain of the transistor.
In an npn bipolar junction transistor (BJT), the reverse bias across the base-collector junction is an important parameter that affects the device's operation. Let's discuss the effect of increasing the reverse bias on the effective base width and the common emitter current gain.
Effect on Effective Base Width:
When the reverse bias across the base-collector junction is increased, it causes the depletion region at the junction to widen. This widening of the depletion region effectively reduces the width of the base region available for the flow of majority charge carriers (electrons in the case of an npn transistor). Therefore, the effective base width decreases.
Effect on Common Emitter Current Gain:
The common emitter current gain (β) of a BJT is defined as the ratio of the collector current (IC) to the base current (IB), i.e., β = IC/IB. It represents the amplification capability of the transistor.
When the reverse bias across the base-collector junction is increased, the depletion region widens, as mentioned earlier. This widening of the depletion region results in a larger electric field across the base region. This electric field accelerates the minority charge carriers (holes in the case of an npn transistor) away from the base-collector junction and towards the collector.
As a result of this increased acceleration, a larger number of minority charge carriers are collected by the collector, resulting in an increased collector current (IC). Since the common emitter current gain is defined as the ratio of IC to IB, an increase in IC without a corresponding change in IB will lead to an increase in β.
Therefore, when the reverse bias across the base-collector junction is increased, the effective base width decreases, and the common emitter current gain increases. So, the correct answer is option 'C'.
Summary:
- Increasing the reverse bias across the base-collector junction of an npn BJT decreases the effective base width.
- Increasing the reverse bias also increases the common emitter current gain of the transistor.
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An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, thena)the effective base width increases and common – emitter current gain increasesb)the effective base width increases and common – emitter current gain decreasesc)the effective base width decreases and common – emitter current gain increasesd)the effective base width decreases and common – emitter current gain decreasesCorrect answer is option 'C'. Can you explain this answer?
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An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, thena)the effective base width increases and common – emitter current gain increasesb)the effective base width increases and common – emitter current gain decreasesc)the effective base width decreases and common – emitter current gain increasesd)the effective base width decreases and common – emitter current gain decreasesCorrect answer is option 'C'. Can you explain this answer? for Electronics and Communication Engineering (ECE) 2024 is part of Electronics and Communication Engineering (ECE) preparation. The Question and answers have been prepared according to the Electronics and Communication Engineering (ECE) exam syllabus. Information about An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, thena)the effective base width increases and common – emitter current gain increasesb)the effective base width increases and common – emitter current gain decreasesc)the effective base width decreases and common – emitter current gain increasesd)the effective base width decreases and common – emitter current gain decreasesCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Electronics and Communication Engineering (ECE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, thena)the effective base width increases and common – emitter current gain increasesb)the effective base width increases and common – emitter current gain decreasesc)the effective base width decreases and common – emitter current gain increasesd)the effective base width decreases and common – emitter current gain decreasesCorrect answer is option 'C'. Can you explain this answer?.
An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, thena)the effective base width increases and common – emitter current gain increasesb)the effective base width increases and common – emitter current gain decreasesc)the effective base width decreases and common – emitter current gain increasesd)the effective base width decreases and common – emitter current gain decreasesCorrect answer is option 'C'. Can you explain this answer? for Electronics and Communication Engineering (ECE) 2024 is part of Electronics and Communication Engineering (ECE) preparation. The Question and answers have been prepared according to the Electronics and Communication Engineering (ECE) exam syllabus. Information about An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, thena)the effective base width increases and common – emitter current gain increasesb)the effective base width increases and common – emitter current gain decreasesc)the effective base width decreases and common – emitter current gain increasesd)the effective base width decreases and common – emitter current gain decreasesCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Electronics and Communication Engineering (ECE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for An npn bipolar junction transistor (BJT) is operating in the active region. If the reverse bias across the base – collector junction is increased, thena)the effective base width increases and common – emitter current gain increasesb)the effective base width increases and common – emitter current gain decreasesc)the effective base width decreases and common – emitter current gain increasesd)the effective base width decreases and common – emitter current gain decreasesCorrect answer is option 'C'. Can you explain this answer?.
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