NEET Physics: Semiconductors Practice Questions
14 free multiple-choice questions on 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 Semiconductors 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. When a semiconductor diode is connected in forward bias, the primary effect observed is:
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Correct answer: A — The forward current increases significantly
In forward bias, the applied positive voltage reduces the potential barrier, allowing a large current to flow easily through the diode, which is the basis of conduction.
Q3. What is the main characteristic of a reverse-biased diode regarding current flow?
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Correct answer: A — It blocks current flow (acts as an open circuit)
When a diode is reverse biased, it acts almost like an open circuit, strongly resisting the flow of current.
Q4. In a half-wave rectifier circuit, the output waveform consists of:
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Correct answer: C — A continuous pulsating DC signal
A half-wave rectifier allows only one half cycle of the input AC to pass through, resulting in a pulsating DC output with only half the input frequency.
Q5. 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.
Q6. In a Zener diode voltage regulator circuit, the constant output voltage is primarily determined by the characteristics of the Zener diode, specifically its:
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Correct answer: D — Zener breakdown voltage
The regulation mechanism in a Zener diode regulator relies entirely on the Zener diode's unique property of maintaining a nearly constant voltage across it when operating in its breakdown region (Zener breakdown voltage, V_Z).
Q7. In a practical rectifier circuit, what component is usually placed across the load resistor in a half-wave rectifier to ensure proper operation?
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Correct answer: A — A series resistor (load)
A load resistor is necessary to draw the current flowing through the diode and the load, establishing the actual power transfer and determining the output voltage characteristics of the circuit.
Q8. The primary function of a photodiode is to convert incident light energy into which form of electrical energy?
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Correct answer: B — Electrical energy
A photodiode operates based on the photoelectric effect, where incident photons are absorbed and generate electron-hole pairs, converting the light energy into electrical current.
Q9. The resistance of a photodiode is generally considered to be:
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Correct answer: C — Inversely proportional to the incident light intensity
When operating in the photoconductive mode, the resistance of the photodiode decreases as the incident light intensity increases because the generated photocurrent increases.
Q10. In a forward-biased diode, the voltage across the diode is generally
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Correct answer: D — Positive
When a diode is forward-biased, it allows current to flow, and the voltage drop across it is positive (approximately 0.7V for Silicon diodes), meaning the voltage across the diode is positive relative to the anode.
Q11. 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.
Q12. 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.
Q13. A photodiode primarily functions as a light sensor by converting incident light energy into what form of energy?
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Correct answer: C — Electrical energy
A photodiode absorbs photons, which generate electron-hole pairs, resulting in a measurable electrical current (photocurrent).
Q14. 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.
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