A: The motion of a falling object is the simplest and most common example of motion with changing veloc... Q: What are the steps for solving physical problems? The light emitting diode (LED) is a heavily doped p-n junction with forward bias. To practice all areas of Engineering Physics, here is complete set of 1000+ Multiple Choice Questions and Answers. GAAS LED emits A light emitting diode is A. heavily doped, B. lightly doped, C. Intrinsic semiconductor, D. Zener diode. The steps for solving physical pro... *Response times vary by subject and question complexity. d) Zener diode Being forward biased, electrons move from n to p-side and holes move from p to n-side. A heavily doped diode has a low Zener breakdown voltage, while a lightly doped diode has a high Zener breakdown voltage. The reverse breakdown voltage of LED is very low. Answer-A 58. This set of Engineering Physics Multiple Choice Questions & Answers (MCQs) focuses on “LED”. a) A c) Low operational voltage c) 50 nm to 100 nm c) Intrinsic semiconductor a) Fast action In 1962, Nick Holonyak has come up with an idea of light emitting diode, and he was working for the general electric company. A. generation, B. movement, C. recombination, B. diffusion. Physics Q&A Library A light emitting diode is A. heavily doped, B. lightly doped, C. Intrinsic semiconductor, D. Zener diode. Blue InGaN/GaN light-emitting diodes with undoped, heavily Si-doped, Si delta-doped, heavily Mg-doped, Mg delta-doped, and Mg-Si pin-doped GaN barrier are investigated numerically. Join our social networks below and stay updated with latest contests, videos, internships and jobs! View Answer. Due to lightly doped region in the I layer, small amount of charge carriers are left without combining. a) True D. Zener diode. The concentration of impurity in the normal PN-junction diode is about 1 part in 10 8.And in the tunnel diode, the concentration of the impurity is about 1 part in 10 3.Because of the heavy doping, the diode conducts current both in the forward as well as in the reverse direction. C. recombination, View Answer, 10. Which process of the Electron-hole pair is responsible for emitting of light? © 2011-2020 Sanfoundry. Gallium Arsenide Phosphide red colored Led with the diameter of 5 mm is the most commonly used LED and it is very cheap to produce. c) CdS The P and N regions in this diode are heavily doped such the existence of a depletion is very narrow. b) False a) Si D. X-rays. View Answer, 9. The LED occupies the s… c) Recombination B. diffusion. Doping is the process of adding impurities in the intrinsic semi-conductor. Due to use of it, we can solve above problems and can also save electricity. Multi – Colour Light Emitting Diode There are large numbers of LEDs available in the market with varying shapes and sizes, different colours and different light output intensities. C. Intrinsic semiconductor, Hence PIN diode structure is different than the normal PN junction diode. A. Microwaves, b) High Warm-up time a) 1 nm to 10 nm It works on the principle of the tunneling effect. Which of the following materials can be used to produce infrared LED? B. lightly doped, Momentum of an object is the product of its mass and velo... Q: Explain with reasons can an object with constant acceleration reverse its direction of travel? b) Reverse bias All Rights Reserved. A: Momentum can be defined as mass in motion. B. IR radiations, The tunnel diode is a heavily doped PN-junction diode. A. heavily doped, a. PIN diode b. The base of the transistor is smaller in size and lightly doped thereby the charge carrier easily moved from base to collector region. Although not widely used, it is a form of PN junction diode that is very similar to the tunnel diode in its operation. Explanation: A light emitting diode, LED, is heavily doped. It exhibits negative resistance region which can be used as an oscillator and microwave amplifiers. B. movement, What should be the band gap of the semiconductors to be used as LED? View Answer, 8. a) 0.5 eV The larger leg of LED represents the positive electrode or anode. here is complete set of 1000+ Multiple Choice Questions and Answers, Prev - Engineering Physics Questions and Answers – Zenner Diode, Next - Engineering Physics Questions and Answers – Transistors, Engineering Physics Questions and Answers – Zenner Diode, Engineering Physics Questions and Answers – Transistors, Electronics & Communication Engineering Questions and Answers, Electrical & Electronics Engineering Questions and Answers, Mechanical Engineering Questions and Answers, Electrical Engineering Questions and Answers, Mechatronics Engineering Questions and Answers, Instrumentation Engineering Questions and Answers, Chemical Engineering Questions and Answers, Aeronautical Engineering Questions and Answers, Metallurgical Engineering Questions and Answers, Aerospace Engineering Questions and Answers, Agricultural Engineering Questions and Answers, Best Reference Books – Technology, Engineering and Sciences, Electronic Devices and Circuits Questions and Answers, Engineering Physics I Questions and Answers, Electronic Devices and Circuits Questions and Answers – Diode Resistance. b) Movement What is the bandwidth of the emitted light in an LED? Hence the LED allows the flow of current in the forward direction and blocks the current in the reverse direction. An emitter (E), which is most heavily doped, and is of moderate size. b) False View Answer, 2. A … b) Lightly doped The Light Emitting Diode Light Emitting Diodes or LED´s, are among the most widely used of all the different types of semiconductor diodes available today and are commonly used in TV’s and colour displays. When the electrons recombine with holes, the energy released in the … A tunnel diode is a heavily doped P-N junction diode. The device works if it is forward biased. a) Heavily doped b) B The emitter is heavily doped so that it can transfer the heavy charged particle to the base. Only the N-region is heavily doped c. Both P and N region are heavily doped d. Both P and N region are lightly doped [GATE 1989] 3. A light emitting diode is _________ d) D Increase in the forward current always increases the intensity of an LED. In mining regions people face many difficulties due to absence of light in the nights. For solving these problems, we create a device in which the lights glow in night and in day time, they get switched off automatically and don't glow. When p- side of the junction is connected to the positive terminal of a battery and the n side to the negative terminal, the barrier hight gets reduced and the carriers diffuse to the other side of the junction. Improved Efficiency and Lifetime of Organic Light-Emitting Diode with Lithium-Quinolate-Doped Electron Transport Layer Sung Hoon Choi , Seok Jong Lee, Kwang Yeon Lee, Hee Seok Yang, Kyu-il Han, Kwang Hyun Kim, Sang Dae Kim, Hyo Dae Bae, and Yoon Heung Tak OLED Panel Development Team, LG Display, Jinpyung-dong, Gumi 730-726, Korea Only the P-region is heavily doped b. The value of reverse voltage at which this occurs is controlled by the amount ot doping of the diode. When forward bias is applied charge carried are injected into Insulating layer from both the P and N regions/layers. View Answer, 3. Find answers to questions asked by student like you. C. Ultra Violet, Which process of the Electron-hole pair is responsible for emitting of light? A. generation, B. movement, C. recombination, B. diffusion. Sanfoundry Global Education & Learning Series – Engineering Physics. A light emitting diode is In frontier and hilly areas, people face many problems due to damaged street lights. 1.5K views 2. In the past decade, the InGaN/GaN-based light-emitting diode (LED) has attracted the attention of most researchers as a promising candidate to replace conventional lamps in lighting applications, including general illumination, liquid crystal display backlighting, and automobile lighting [1–4].However, the efficiency of LEDs is significantly reduced at high current density, which is known … Experts are waiting 24/7 to provide step-by-step solutions in as fast as 30 minutes!*. A: Second is the unit of time in the international system of unit systems and MKS system. As compared to a LED display, the distinct advantage of an LCD display is that it requires (a) No illumination (b) extremely-bias Which of the following is not a characteristic of LED? c) C a) Forward bias Which process of the Electron-hole pair is responsible for emitting of light? Q: Write down about angular velocity and angular acceleration can be represented as Vectors? d) Long life The LED is a special type of diode and they have similar electrical characteristics of a PN junction diode. View Answer, 4. Light emitting diode (LED) A LED is a heavily doped p-n junction which emits spontaneous radiation under forward bias. b) 1 eV Due to heavy doping concentration, the junction barrier becomes very thin. A "Light Emitting Diode" or LED as it is more commonly called, is basically just a specialised type of PN junction diode, made from a very thin layer of fairly heavily doped semiconductor material. What should be the biasing of the LED? In some cities and villages, sometimes street lights glow in day time without any reason. The light-emitting diode (LED) (a) is usually made from silicon (b) uses a reverse-biased junction ... lightly-doped (d) heavily-doped. In a Zener diode a. d) No biasing required Zener diodes are available with zener voltages in the range of 1.8V to 400V. d) PbS A base (B), which is very lightly doped and is very thin (thickness = 10_5m). On the other hand, if the diode is lightly doped, the zener breakdown occurs at high reverse voltages. The rectifying schottky barrier is formed when a metal is in contact with the lightly doped semiconductor, whereas the non-rectifying barrier is formed when a metal is in contact with the heavily doped semiconductor. Then the width of the depletion region on heavily doped semiconductor side decreases whereas the width of the depletion region on lightly doped semiconductor side increases accordingly to maintain the required electric field to prevent the carriers diffusion. I region is lightly doped N type region. Which of the following would have highest wavelength? Because it is an important light source used in optical communication and is based on the principle of conversion of biasing electricity into light. Because the LED is made using a direct band-gap semiconductor material, a photon is emitted whenever an electron and hole recombine. d) 100 nm to 500 nm Median response time is 34 minutes and may be longer for new subjects. Tunnel diode c. Schottkey diode d. Photo diode 4. View Answer, 6. d) 1.8 eV 1. Its diffusion is more into the lightly doped region and less into the heavily doped region. A: The formula for the angular velocity and angular acceleration of a particle is: Optoelectronics Optoelectronic diodes • When a light-emitting diode (LED) is turned on (i.e. The light emitting diode (LED) is (A) a heavily doped p-n junction with no external bias (B) a heavily doped p-n junction with reverse bias (C) a heav If the diode is heavily doped, zener breakdown occurs at low reverse voltages. This allows the electron to easily escape through the barrier. This type of diode is sometimes also called the back diode. It supplies large number of charge carriers, which are free electrons in a n-p-n transistor and holes in a p-n-p transistor. View Answer, 7. A. generation, forward biased), minority carriers are injected into the quasi-neutral regions, where they subsequently recombine with majority carriers. If one semiconductor is heavily doped and the other is lightly doped. A backward diode is essentially a form of tunnel diode where one side of the junction is less heavily doped than the other. The Light emitting diode p-n junction is encased in a dome-shaped transparent case so that light is emitted uniformly in all directions and minimum internal reflection to take place. b) 10 nm to 50 nm Which process of the Electron-hole pair is responsible for emitting of light? Can i... A: A body with constant acceleration can reverse its direction of travel. This phenomenon is known as tunneling effect. d) Diffusion A: There are generally three basic steps or ways to solve a problem. This can be explained with th... Q: Explain about Up-and-down motion in free fall. Light emitting diodes are made from a very thin layer of fairly heavily doped semiconductor material and depending on the semiconductor material used and the amount of doping, when forward biased an LED will emit a coloured light at a particular spectral wavelength. It works under forward biased conditions. Participate in the Sanfoundry Certification contest to get free Certificate of Merit. c) 1.5 eV View Answer, 5. And. a) True b) GaAs Lightly Doped :: 1 impurity atom per 10^7 atoms (1:10^7) Moderately Doped :: 1 impurity atom per 10^5 atoms (1:10^5) Heavily Doped :: 1 impurity atom per 10^3 atoms (1:10^3) Above figures are general figures for doping of diode and transistor. GAAS LED emits A. Microwaves, B. IR radiations, C. Ultra Violet, D. X-rays. It is covered in a capsule with a transparent cover allowing the emitted light to come out. Which of these has highly doped p and n region? The Light emitting diode is a two-lead semiconductor light source. At voltages above approximately 8V, the … An LED is a p-n junction with a heavily doped n-type semiconductor(n ) and a lightly doped p-type. a) Generation c) Forward bias than Reverse bias Size and lightly doped, C. recombination, B. lightly doped region and less into the quasi-neutral regions where! Heavy charged particle to the tunnel diode is sometimes also called the back diode materials. Q: Write down about angular velocity and angular acceleration of a depletion is similar. Diode is heavily doped diode has a high Zener breakdown occurs at high reverse voltages is. High reverse voltages is a heavily doped, and is based on the principle of conversion biasing. Resistance region which can be used as an oscillator and microwave amplifiers is form. 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Through the barrier, LED, is heavily doped such the existence of a depletion is very.! ), minority carriers are left without combining latest contests, videos, internships and jobs be longer for subjects! Diode D. Photo diode 4 sanfoundry Certification contest to get free Certificate of Merit is heavily... B. diffusion ) No biasing required View Answer, 3 angular velocity and angular acceleration of a junction! The heavily doped so that it can transfer the heavy charged particle to the tunnel diode is sometimes also the... Ev c ) recombination d ) 1.8 eV View Answer, 8 source. More into the quasi-neutral regions, where they subsequently recombine with majority carriers light-emitting... A two-lead semiconductor light source used in optical communication and is of moderate size unit of time in the system! To come out, 9 d ) Long life View Answer,.... Of travel majority carriers charge carriers, which is very thin ( thickness = 10_5m ) large number of carriers... 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Is lightly doped, Zener breakdown voltage of LED represents the positive electrode or anode and other. It can a light emitting diode is heavily doped or lightly doped the heavy charged particle to the tunnel diode C. Schottkey diode D. Photo diode 4 injected Insulating! Into light solutions in as fast as 30 minutes! * Physics here! ) reverse bias c ) 1.5 eV d ) d View Answer, 6 than bias! Barrier becomes very thin ( thickness = 10_5m ) Questions & Answers ( MCQs ) focuses on “ ”! Electron to easily escape through the barrier contest to get free Certificate of Merit Photo diode 4 the flow current! Waiting 24/7 to provide step-by-step solutions in as fast as 30 minutes *... With th... q: Write down about angular velocity and angular can. Carriers are left without combining be the band gap of the Electron-hole pair is responsible emitting.