Consider the following statements :
(A) The junction area of solar cell is made very narrow compared to a photo diode.
(B) Solar cells are not connected with any external bias.
(C) LED is made of lightly doped p-n junction.
(D) Increase of forward current results in continuous increase of LED light intensity.
(E) LEDs have to be connected in forward bias for emission of light.
(A) The junction area of solar cell is made very narrow compared to a photo diode.
(B) Solar cells are not connected with any external bias.
(C) LED is made of lightly doped p-n junction.
(D) Increase of forward current results in continuous increase of LED light intensity.
(E) LEDs have to be connected in forward bias for emission of light.
- (A)B, D, E Only
- (B)A, C Only
- (C)A, C, E Only
- (D)B, E Only✓ Correct
Answer: (D)
Solution
Check each statement against the physics of p-n junction optoelectronic devices.
(A) False — a solar cell needs a large junction area to capture as much incident light as possible; a photodiode instead uses a narrow junction for fast response.
(B) True — a solar cell is itself a source of emf generated by the photovoltaic effect and requires no external bias.
(C) False — an LED junction is heavily doped on both sides to allow high carrier injection and efficient radiative recombination, not lightly doped.
(D) False — LED light intensity increases with forward current only up to a point; beyond that it saturates and can fall due to junction heating.
(E) True — an LED must be forward biased so that electrons and holes are injected across the junction and recombine to emit photons.
Only statements B and E are correct.
(A) False — a solar cell needs a large junction area to capture as much incident light as possible; a photodiode instead uses a narrow junction for fast response.
(B) True — a solar cell is itself a source of emf generated by the photovoltaic effect and requires no external bias.
(C) False — an LED junction is heavily doped on both sides to allow high carrier injection and efficient radiative recombination, not lightly doped.
(D) False — LED light intensity increases with forward current only up to a point; beyond that it saturates and can fall due to junction heating.
(E) True — an LED must be forward biased so that electrons and holes are injected across the junction and recombine to emit photons.
Only statements B and E are correct.
JEE Main · 2025 · 24 Jan 2025 · Shift 1 · Single correct option