Advertisements
Advertisements
प्रश्न
Sunil and his parents were travelling to their village in their car. On the way his mother noticed some grey coloured panels installed on the roof of a low building. She enquired from Sunil what those panels were and Sunil told his mother that those were solar panels.
(a) What were the values displayed by Sunil and his mother? State one value for each.
(b) In what way would the use of solar panels prove to be very useful?
(c) Name the semiconductor device used in solar panels. Briefly explain with the help of a diagram, how this device works
Advertisements
उत्तर
(a) The value displayed by Sunil is awareness and the value displayed by Sunil's mother is curiosity.
(b) The use of solar panels would prove to be useful because
- It harnesses solar energy that is free from all kinds of pollution. Thus, they are eco-friendly.
- It is highly durable and, hence, requires no maintenance.
(c) Semiconductor device used in solar panels is solar cell.
It is a semiconductor device used to convert photons of solar light into electricity.
It generates emf when solar radiation fall on the p-n junction.
-
A p-type silicon wafer of about 300 μm is taken over which a thin layer of n-type silicon is grown on one side by diffusion process.
-
The generation of emf by a solar cell when light falls on it is due to following three processes:
-
The light close to the junction generates e-h pairs.
-
The electric field of the depletion region separates the electrons and holes.
-
The electrons reaching the n-side are collected by the front contact, while the holes reaching the p-side are collected by the back contact. Thus, the p-side becomes positively charged and the n-side becomes negatively charged, giving rise to photovoltage.
-
- Semiconductors with band gaps close to 1.5 eV are ideal materials for the fabrication of solar cells.
- V-I characteristic of a solar cell:
The V-I characteristic of a solar cell as follows:
Isc is the short-circuit current when the load resistance RL is zero.
Voc is the open-circuit voltage when RL is infinity.
APPEARS IN
संबंधित प्रश्न
With the help of a neat circuit diagram, explain the working of a photodiode.
How is a Zener diode fabricated?
Explain with the help of a diagram, how depletion region and potential barrier are formed in a junction diode.
Using the necessary circuit diagrams, show how the V-I characteristics of a p-n junction are obtained in
Reverse biasing
How are these characteristics made use of in rectification?
Why is zener diode fabricated by heavily doping both p- and n-sides of the junction?
How is a photodiode fabricated?
The plate resistance of a triode is 8 kΩ and the transconductance is 2.5 millimho. (a) If the plate voltage is increased by 48 V and the grid voltage is kept constant, what will be the increase in the plate current? (b) With plate voltage kept constant at this increased value, by how much should the grid voltage be decreased in order to bring the plate current back to its initial value?
Write the important considerations which are to be taken into account while fabricating a p-n junction diode to be used as a Light Emitting Diode (LED). What should be the order of band gap of an LED, if it is required to emit light in the visible range? Draw a circuit diagram and explain its action.
Why a photo-diode is operated in reverse bias whereas the current in the forward bias is much larger than that in the reverse bias? Explain. Mention its two uses.
Draw the circuit diagram of an illuminated photodiode and its I-V characteristics.
