Question

Identify the electronic components from the following symbols. Write any one difference between them.

Answer 1

Hint:We know that a diode is a semiconductor device which lets the flow of current only in one direction and provides great resistance in the opposite direction. It has two terminals - (i) Positive terminal, and (ii) Negative Terminal. A simple Diode is represented by this symbol –

It looks very similar to the symbol given in the question, so it is clear that the symbol represents a diode; now, we need to determine the type of diode.

Complete step by step answer:
Given: In the two symbols given, the two arrows above the diode symbol means "the Light," which means that these symbols represent a diode type that interacts with the light.
Now considering the first symbol (a), we see that the diode shown in the symbol is emitting the light, which means that this diode is a "Light Emitting Diode," also known as the "LED." An LED is a semiconductor device that emits the light (photons) when the current flows through it.Similarly, considering the symbol (b), we see that the figure's diode absorbs the light incident upon it. This type of diode is known as the "PhotoDiode." The photodiode is a diode which generates an electric current when the light (photons) are absorbed by it. To absorb the light efficiently, some arrangements are attached to the photodiode, such as the optical fibers, focus lenses, etc.Therefore, the symbol (a) represents a Light Emitting Diode (LED), and the symbol (b) represents a Photodiode.
The one important difference between a Light Emitting Diode (LED) and a Photodiode is that –
 "The LED emits the Light from it while the PhotoDiode absorbs the Light incident upon it", or we can say that "the LED converts the electrical energy into the Light (Photon) Energy while the PhotoDiode converts the Light (Photon) Energy into the Electrical Energy."

Note: We know that the working of an LED and the PhotoDiode is opposite to each other, but an LED could also be used as the Photodiode. This is possible because an LED is sensitive to the light having similar wavelengths as the light it emits when the current is flown through it.