Question

Consider the following statements: 
A. The junction area of a solar cell is made very narrow compared to a photodiode.
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 a continuous increase in 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

Hint:

Remember that in LEDs, forward bias is essential for the emission of light. Solar cells, on the other hand, generate voltage without the need for external bias.

Answer 1

The Correct Option is D

To resolve the problem, evaluate the validity of each statement concerning solar cells, photodiodes, and LEDs. Analyze each statement individually:

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

This statement is false. Solar cell junction areas are typically larger to maximize sunlight absorption and current generation. Photodiode junction areas are optimized for speed and sensitivity in specific applications.

1. Statement B: "Solar cells are not connected with any external bias."
2. Statement C: "LED is made of lightly doped p-n junction."

This statement is false. LEDs are constructed with heavily doped p-n junctions to promote efficient electron-hole recombination, essential for light emission.

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

This statement is generally true within operational limits. However, exceeding maximum current ratings can damage the LED or cause efficiency droop. Within typical operating ranges, the statement is valid.

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

This statement is true. Forward biasing LEDs enables charge carriers to recombine and emit light.

Based on this analysis, statements B and E are correct. Thus, the correct selection is: B, E Only.