NEET Physics: p-n junction diode characteristics Practice Questions
15 free multiple-choice questions on p-n junction diode characteristics (Semiconductors) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. If a diode is operating in the forward bias region, what is the relationship between the applied forward voltage (V_F) and the resulting current (I_F), assuming constant temperature?
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Correct answer: D — I_F is exponentially related to V_F
The forward current flow across a diode is governed by the Shockley diode equation, showing an exponential relationship between forward voltage and forward current.
Q2. If the doping concentration of the P-side is significantly higher than the N-side, the depletion region will be located primarily in the:
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Correct answer: B — P-side
The depletion region extends further into the lightly doped side (N-side) because the voltage drop is distributed differently based on the doping levels and the width of the depletion region.
Q3. In the reverse-biased condition of a p-n junction diode, what is the primary physical effect on the depletion region?
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Correct answer: C — Depletion region widens
When the diode is reverse-biased, the electric field increases, causing the depletion region to widen, leading to increased reverse leakage current.
Q4. When a p-n junction diode is connected in forward bias, what happens to the potential barrier across the junction?
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Correct answer: B — The potential barrier decreases
In forward bias, the external voltage opposes the built-in potential, thus reducing the potential barrier, allowing significant current flow.
Q5. The phenomenon responsible for the establishment of a potential difference across the p-n junction is known as:
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Correct answer: C — Built-in potential (or barrier potential)
The built-in potential (V₀) is the potential difference across the junction established due to the diffusion of carriers and the resulting charge separation.
Q6. The barrier potential across a p-n junction diode is primarily established by:
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Correct answer: D — The arrangement of the depletion region and the band bending
The barrier potential (built-in potential) is established due to the diffusion of minority carriers and the resulting charge separation across the depletion region, which dictates the band bending.
Q7. Which statement correctly describes the behavior of a p-n junction diode when it is reverse-biased?
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Correct answer: D — The diode acts as an open circuit
In reverse bias, the diode acts as an open circuit (an insulator) for the majority carriers, blocking current flow (except for very small reverse leakage).
Q8. In reverse bias condition, what happens to the width of the depletion region in the p-n junction diode?
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Correct answer: C — It increases
Applying reverse bias increases the electric field across the junction, causing the depletion region to widen (increase in width).
Q9. Under reverse bias condition, what is the primary effect on the current flow in an ideal diode?
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Correct answer: C — Virtually no current flows
In reverse bias, the external voltage adds to the built-in potential, strongly opposing the flow of majority carriers, resulting in negligible current flow (ideally zero).
Q10. Which mechanism is responsible for the flow of current in the forward-biased p-n junction diode?
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Correct answer: B — Diffusion of minority carriers
In forward bias, majority carriers (holes from p-side and electrons from n-side) diffuse across the junction, leading to current flow.
Q11. What is the concept behind the breakdown mechanism that allows a diode to conduct unexpectedly under high reverse voltage?
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Correct answer: B — Avalanche effect
The breakdown phenomenon (like Zener breakdown) occurs due to the avalanche effect where high electric fields cause carriers to gain sufficient energy to cause impact ionization.
Q12. When a p-n junction is reversely biased, the majority carriers in the bulk material are pushed:
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Correct answer: D — away from the junction boundary
In reverse bias, the applied voltage increases the potential barrier, pushing the majority carriers (holes in P and electrons in N) further away from the junction boundary.
Q13. The region of the p-n junction where the concentration of majority carriers is significantly reduced is known as the:
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Correct answer: C — Depletion region
The depletion region is the region devoid of mobile charge carriers (majority carriers) due to the formation of the built-in electric field.
Q14. When a p-n junction diode is forward biased, the potential barrier across the junction is:
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Correct answer: D — Decreased
Forward biasing reduces the potential barrier across the junction, allowing majority carriers to flow easily across the junction.
Q15. What is the approximate potential barrier height (V₀) that must be overcome for a p-n junction diode to conduct in forward bias?
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Correct answer: D — Barrier potential (V₀)
Conduction in a forward-biased diode requires the applied voltage to overcome the potential barrier (V₀) established across the depletion region, which is related to the built-in potential (V₍bi)).
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