PHOTOCONDUCTIVITY.pptxbdhshshwjjwjjwjwjhqh

Sure, here’s a random 3000-word story:


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Title: "The Hidden Village"

Nestled deep within the mountains, beyond the reach of modern civilization, lay a village few knew about. It was called Aravien, and it thrived in the shadows of towering pines and hidden valleys. The people of Aravien lived simple, harmonious lives, unaware of the outside world’s

Sure, here’s a random 3000-word story:


---

Title: "The Hidden Village"

Nestled deep within the mountains, beyond the reach of modern civilization, lay a village few knew about. It was called Aravien, and it thrived in the shadows of towering pines and hidden valleys. The people of Aravien lived simple, harmonious lives, unaware of the outside world’s

Sure, here’s a random 3000-word story:


---

Title: "The Hidden Village"

Nestled deep within the mountains, beyond the reach of modern civilization, lay a village few knew about. It was called Aravien, and it thrived in the shadows of towering pines and hidden valleys. The people of Aravien lived simple, harmonious lives, unaware of the outside world’s
Sure, here’s a random 3000-word story:


---

Title: "The Hidden Village"

Nestled deep within the mountains, beyond the reach of modern civilization, lay a village few knew about. It was called Aravien, and it thrived in the shadows of towering pines and hidden valleys. The people of Aravien lived simple, harmonious lives, unaware of the outside world’s

Sure, here’s a random 3000-word story:


---

Title: "The Hidden Village"

Nestled deep within the mountains, beyond the reach of modern civilization, lay a village few knew about. It was called Aravien, and it thrived in the shadows of towering pines and hidden valleys. The people of Aravien lived simple, harmonious lives, unaware of the outside world’s

Sure, here’s a random 3000-word story:


---

Title: "The Hidden Village"

Nestled deep within the mountains, beyond the reach of modern civilization, lay a village few knew about. It was called Aravien, and it thrived in the shadows of towering pines and hidden valleys. The people of Aravien lived simple, harmonious lives, unaware of the outside world’s

Sure, here’s a random 3000-word story:


---

Title: "The Hidden Village"

Nestled deep within the mountains, beyond the reach of modern civilization, lay a village few knew about. It was called Aravien, and it thrived in the shadows of towering pines and hidden valleys. The people of Aravien lived simple, harmonious lives, unaware of the outside world’s

Sure, here’s a random 3000-word story:


---

Title: "The Hidden Village"

Nestled deep within the mountains, beyond the reach of modern civilization, lay a village few knew about. It was called Aravien, and it thrived in the shadows of towering pines and hidden valleys. The people of Aravien lived simple, harmonious lives, unaware of the outside world’s

Sure, here’s a random 3000-word story:


---

Title: "The Hidden Village"

Nestled deep within the mountains, beyond the reach of modern

1. PHOTOCONDUCTIVITY VISMAYA S 2301105028

2. Photoconductivity is the optical property of light. Discovered by Willoughby Smith in 1873. The term photoconductivity is derived from two words ‘photo’ ,which means ‘photon of light’ and ‘conductivity’ which means ‘movement of current of charge carrier in semiconductor’. So the whole term means ‘variations of changes of current due to incident light’.

3. DEFINITION: It is the effect of increasing electrical conductivity in a solid due to light absorption.When the so-called internal photo effect takes place, the energy absorbed enables the transition of activator electrons into the conduction band and the charge exchange of traps with holes being created in the valence band. In the process,the number of charge carriers in the crystal lattice increases and as a result, the conductivity is enhanced. Photoconductivity is an optical and electrical phenomenon in which a material become more electrically conductive due to the absorption of electromagnetic radiation such as visible light, ultraviolet light, infrared light, or gamma radiations.

4. When light is absorbed by a material such as a semiconductor, the number of electron hole pairs increases resulting in the increase in the number of charge carriers and raises its electrical conductivity.

5. WHEN DOES PHOTOCONDUCTIVITY OCCUR? To cause excitation, the photon( hv ) that strikes the semiconductor must have enough energy to raise electrons across the band gap, or to excite the impurities within the band gap( Eg )• If Eg be the minimum band gap,then the longest wavelength which may cause this effect is λ= hc / Eg

6. TYPES OF PHOTOCONDUCTIVITY Intrinsic photoconductors : Absorption across primary band gap ( Eg ) creates electron and hole photocarriers. Extrinsic photoconductors: Absorption from(or to) impurity site in gap creates photocarriers in conduction or valence band.

7. SPECTRAL RESPONSE The variation of photoconductivity with photon energy is known as spectral response. The maximum value of photocurrent corresponds to band gap energy and spectral response .

8. PHOTOCONDUCTIVE MATERIALS Advantages Mainly depend on light,so their resistance will decrease when light drops on them. They are cheap and are available in different sizes and shapes. They need less power and voltage for operation. They are used to make simple circuit. Disadvantages Less responsive as compared to phototransistors and photodiodes. When Cadmium sulfide is used in the construction of photo resistors, it is dangerous to the atmosphere. Their respond time is very slow. They are sensitive to temperature.

9. USES OF PHOTOCONDUCTIVE MATERIALS Photoconductors are used for X-ray image detectors. Used for relay control. Used to switch ON and OFF transistors. Used to control the level of current flow in LED. Used in the process of Xerography or photocopying.

10. THANKYOU