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.

Choose the correct answer from the options given below :

<p><strong>Statement A: The junction area of solar cell is made very narrow compared to a photo diode.</strong></p> <ul> <li><p>Let's think about the purpose of a solar cell. Its main job is to collect as much sunlight as possible to generate electricity.</p></li> <li><p>To collect more light, it needs a larger surface area. Therefore, the $p-n$ junction of a solar cell is made with a <strong>very large area</strong> (typically a few square centimeters).</p></li> <li><p>This statement says the area is narrow, which is the opposite. So, statement A is <strong>Incorrect</strong>.</p></li> </ul> <p><strong>Statement B: Solar cells are not connected with any external bias.</strong></p> <ul> <li><p>Remember, a solar cell is like a small battery. It <em>generates</em> an electromotive force (e.m.f.) or voltage when light shines on it. It gives power; it doesn't take power from an external battery to work.</p></li> <li><p>We don't apply any external bias to it. We simply connect a load, like a bulb, across it to use the electricity it produces.</p></li> <li><p>So, statement B is <strong>Correct</strong>.</p></li> </ul> <p><strong>Statement C: LED is made of lightly doped p-n junction.</strong></p> <ul> <li><p>An LED (Light Emitting Diode) works by the recombination of electrons and holes at the junction. To get bright light, we need a very high rate of recombination.</p></li> <li><p>A high rate of recombination is only possible if there are a large number of electrons on the n-side and holes on the p-side.</p></li> <li><p>To achieve this high concentration of charge carriers, the $p-n$ junction of an LED is <strong>heavily doped</strong>, not lightly doped.</p></li> <li><p>So, statement C is <strong>Incorrect</strong>.</p></li> </ul> <p><strong>Statement D: Increase of forward current results in continuous increase of LED light intensity.</strong></p> <ul> <li><p>It is true that the intensity of light from an LED increases as we increase the forward current. More current means more electrons and holes are crossing the junction and recombining per second, which produces more light.</p></li> <li><p>However, we cannot increase the current indefinitely. Every LED has a maximum current rating mentioned by the manufacturer. If we pass a current higher than this safe limit, the LED will overheat and get permanently damaged.</p></li> <li><p>So, the increase is not "continuous" without any limit.</p></li> <li><p>Therefore, this statement is <strong>Incorrect</strong>.</p></li> </ul> <p><strong>Statement E: LEDs have to be connected in forward bias for emission of light.</strong></p> <ul> <li><p>This is the basic condition for an LED to work. When we connect it in forward bias, the potential barrier at the junction is lowered.</p></li> <li><p>This allows the majority carriers to flow across the junction and recombine. This recombination process releases energy in the form of light (photons).</p></li> <li><p>In reverse bias, the barrier height increases, very little current flows, and no light is emitted.</p></li> <li><p>So, statement E is <strong>Correct</strong>.</p></li> </ul> <p><strong>Final Conclusion:</strong></p> <p>Based on our step-by-step analysis, the only correct statements are <strong>B and E</strong>.</p> <p>Looking at the options provided:</p> <p>Option A: A, C, E Only</p> <p>Option B: B, E Only</p> <p>Option C: A, C Only</p> <p>Option D: B, D, E Only</p> <p>Thus, the correct choice is <strong>Option B</strong>.</p>