JEE Physics 2025 Question with Solution

Given: Five statements about solar cells, photodiodes, and LEDs are to be checked for correctness.

Find: Which combination of statements is correct.

Check each statement one by one:

1. Statement A: The junction area of a solar cell is made very narrow compared to a photodiode.

This is incorrect. A solar cell generally has a larger junction area so that it can absorb more sunlight and produce more current.

2. Statement B: Solar cells are not connected with any external bias.

This is correct. A solar cell works by the photovoltaic effect and generates emf on its own, so no external bias is required.

3. Statement C: LED is made of lightly doped p-n junction.

This is incorrect. An LED is typically made using a heavily doped p-n junction to promote efficient electron-hole recombination and light emission.

4. Statement D: Increase of forward current results in a continuous increase in LED light intensity.

From the solution analysis, this statement is taken as incorrect because the increase does not continue indefinitely; beyond a range, heating and device limitations prevent a continuous rise in intensity.

5. Statement E: LEDs have to be connected in forward bias for emission of light.

This is correct. In forward bias, electrons and holes recombine and emit photons.

Therefore, the correct statements are B and E only. Hence, the correct option is D.

Given: Statements A to E discuss properties of solar cells and LEDs.

Find: The correct set of true statements.

• A is false because solar cells are designed with a larger area to collect more incident light.
• B is true because solar cells are operated without external bias.
• C is false because LEDs are not lightly doped; heavy doping helps radiative recombination.
• D is false in the intended exam sense because LED intensity does not increase continuously without limit as current increases.
• E is true because light emission from an LED occurs in forward bias.

So only B and E are correct. This matches Option D.