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Two p-n junction diodes are connected back to back to make a transistor. Which one of the following is correct?
- a)The current gain of such a transistor will be high
- b)The current gain of such a transistor will be moderate
- c)It cannot be used as a transistor due to large base width
- d)It can be used only for p-n-p transistor
Correct answer is option 'C'. Can you explain this answer?
Verified Answer
Two p-n junction diodes are connected back to back to make a transisto...
A transistor operation needs very small base width to allow the minority carriers, drifted from emitter to diffuse into collector.
By connecting two PN diodes back to back the transistor will have wide base causing the minority carriers from emitter to recombine in base region before they diffuse into collector. This reduces collector current or cut off entirely.
Most Upvoted Answer
Two p-n junction diodes are connected back to back to make a transisto...
Understanding the Back-to-Back P-N Junction Diode Configuration
When two p-n junction diodes are connected back-to-back, they create a junction that does not function like a traditional transistor. Below are key points explaining why this configuration cannot effectively be used as a transistor.
Large Base Width
- The primary reason this configuration cannot serve as a transistor is due to the large base width.
- In a typical bipolar junction transistor (BJT), the base is thin to allow efficient recombination and transport of charge carriers. A large base width reduces the current gain significantly.
Lack of Current Gain
- A transistor relies on a small input current to control a larger output current. However, in the back-to-back diode configuration, the lack of a properly designed base region means that the current gain (beta) is very low or non-existent.
- This results in a device that cannot amplify current effectively, which is a fundamental characteristic of a transistor.
Operational Limitations
- The back-to-back diode setup lacks the control mechanisms present in BJTs or FETs. This limits its functionality in applications requiring amplification or switching.
- The recombination of charge carriers in a wide base leads to significant losses, making it inefficient for transistor applications.
Conclusion
- While back-to-back diodes can exhibit some electronic properties, they do not meet the necessary criteria to function as a transistor. Hence, option “C” is correct: It cannot be used as a transistor due to large base width.
When two p-n junction diodes are connected back-to-back, they create a junction that does not function like a traditional transistor. Below are key points explaining why this configuration cannot effectively be used as a transistor.
Large Base Width
- The primary reason this configuration cannot serve as a transistor is due to the large base width.
- In a typical bipolar junction transistor (BJT), the base is thin to allow efficient recombination and transport of charge carriers. A large base width reduces the current gain significantly.
Lack of Current Gain
- A transistor relies on a small input current to control a larger output current. However, in the back-to-back diode configuration, the lack of a properly designed base region means that the current gain (beta) is very low or non-existent.
- This results in a device that cannot amplify current effectively, which is a fundamental characteristic of a transistor.
Operational Limitations
- The back-to-back diode setup lacks the control mechanisms present in BJTs or FETs. This limits its functionality in applications requiring amplification or switching.
- The recombination of charge carriers in a wide base leads to significant losses, making it inefficient for transistor applications.
Conclusion
- While back-to-back diodes can exhibit some electronic properties, they do not meet the necessary criteria to function as a transistor. Hence, option “C” is correct: It cannot be used as a transistor due to large base width.
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Two p-n junction diodes are connected back to back to make a transistor. Which one of the following is correct?a)The current gain of such a transistor will be highb)The current gain of such a transistor will be moderatec)It cannot be used as a transistor due to large base widthd)It can be used only for p-n-p transistorCorrect answer is option 'C'. Can you explain this answer? for Electrical Engineering (EE) 2026 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about Two p-n junction diodes are connected back to back to make a transistor. Which one of the following is correct?a)The current gain of such a transistor will be highb)The current gain of such a transistor will be moderatec)It cannot be used as a transistor due to large base widthd)It can be used only for p-n-p transistorCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2026 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Two p-n junction diodes are connected back to back to make a transistor. Which one of the following is correct?a)The current gain of such a transistor will be highb)The current gain of such a transistor will be moderatec)It cannot be used as a transistor due to large base widthd)It can be used only for p-n-p transistorCorrect answer is option 'C'. Can you explain this answer?.
Two p-n junction diodes are connected back to back to make a transistor. Which one of the following is correct?a)The current gain of such a transistor will be highb)The current gain of such a transistor will be moderatec)It cannot be used as a transistor due to large base widthd)It can be used only for p-n-p transistorCorrect answer is option 'C'. Can you explain this answer? for Electrical Engineering (EE) 2026 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about Two p-n junction diodes are connected back to back to make a transistor. Which one of the following is correct?a)The current gain of such a transistor will be highb)The current gain of such a transistor will be moderatec)It cannot be used as a transistor due to large base widthd)It can be used only for p-n-p transistorCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2026 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Two p-n junction diodes are connected back to back to make a transistor. Which one of the following is correct?a)The current gain of such a transistor will be highb)The current gain of such a transistor will be moderatec)It cannot be used as a transistor due to large base widthd)It can be used only for p-n-p transistorCorrect answer is option 'C'. Can you explain this answer?.
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