महाराणा प्रताप ट्रेल सज्जनगढ़ उदयपुर में इको ट्रेल 30 नवम्बर को राजस्थान वन विभाग उदयपुर डिविजन तथा WWF-India उदयपुर डिविजन के सानिध्य में महाराणा प्रताप ट्रेल सज्जनगढ़ उदयपुर में इको ट्रेल की गई, जिसमें WWF-India के स्टेट काॅर्डिनेटर श्रीमान अरूण सोनी तथा वन विभाग कीे ओर से डाॅ. सतीश कुमार शर्मा, सेवानिवृत्त अधिकारी मौजूद थे। मुझे भी इस इको ट्रेल में जाने का सुअवसर प्राप्त हुआ, जो गोरीला व्यू पाॅइंट से बड़ी-लेक व्यू पाॅइंट तक की गई इसमें मुझे विज्ञान की एक नई शाखा के बारे में पता चला, जिसे टट्टी विज्ञान कहा जाता है। सुनने में आपको थोड़ा अजीब लगेगा, मुझे भी सुनकर हैरानी हुई, परन्तु वास्तव में एक ऐसा भी विज्ञान है, जिसके बारे में डाॅ. सतीश शर्मा ने बड़े ही विस्तार पूर्वक बताया कि किस प्रकार वनों में जानवरों की टट्टी देखकर यह पता लगाया जा सकता है कि यहां कौनसा जानवर आया था। जानवरों की टट्टी कितनी पुरानी है, वह गीली है या सूखी है। इसी के आधार पर उस विशेष जंगल में कौन-कौनसे जानवर विचरण करते हैं, उसके बारे में वन विज्ञान के कर्मचारी पता लगा लेते हैं। जानवरों की टट्टी का विश्लेषण करके यह पता लगा...
Breakdown and resistance of diode
Breakdown of a diode
- On applying reverse bias to the diode, two types of breakdown occurs, which are responsible to the sudden increase of current in the reverse bias condition.
Avalanche breakdown
- In this mechanism, the minority charge carriers gain enough kinetic energy from the applied reverse voltage to collide with the valence electrons of the atom and liberate them.
- In this process the covalent bond breaks and create a large number of electron-hole pairs.
- The new charge carriers so produced generate the additional electron-hole pairs.
- In this way the number of free electrons and holes increases continuously.
- This phenomenon is known as avalanche multiplication and it produces a sharp increase in the reverse current.
- The magnitude of avalanche breakdown voltage can be increased by increasing the temperature.
Zener breakdown
- If the junctions are heavily doped and have a very narrow depletion region, then the breakdown occurs is known as Zener breakdown.
- Since in this case there exist a high electric field (E = V/d), across the junction.
- This electric field is so strong to break the covalent bond and generate the electron-hole pairs.
- On further increasing the Zener voltage, the large number of carriers generate, which increase the reverse current suddenly.
- This breakdown is a field emission phenomena.
- On increasing the temperature the Zener breakdown voltage can be decreased.
Resistance of a diode
Static or dc resistance
- When only dc current flows through the diode, then the resistance offered by it is static or dc resistance.
- It is the ratio of the dc voltage across the diode to the dc current flowing through it.
- Rdc = V / I
- In forward bias the static resistance of diode is RF and in reverse bias RR.
- RR >> RF
- For Ge, RR : RF = 4000 : 1.
Dynamic or ac resistance
- When only ac current or a small ac current along with dc current flows through the diode, then the resistance offered by it is dynamic or ac resistance.
- It is reciprocal of the slope of the current-voltage characteristic of the diode.
- Rac = ΔV / ΔI
- When the diode is sufficiently forward biased, then at any temperature T
- Here k = Boltzmann constant, and e = charge of electron.
- For Ge, η = 1, and at T = 300 K
- Rac = 26 / I
To know more about breakdown and resistance of diode please click on https://youtu.be/T39lWWPfLFo
In hardware, a LED circuit or LED driver is an electrical circuit used to power a light-producing diode (LED). The circuit should give adequate current to light the LED at the necessary splendor, yet should restrict the current to forestall harming the LED. If you want to know more, Please check out here - official site
ReplyDelete