Draw the symbol of LED & photodiode. 

1 Answer

Answer :

Symbol of LED & photodiode

image

Related questions

Description : Draw symbol of LED and explain it’s working principle.

Last Answer : Construction of LED: The basic structure of LED is shown in fig.(a). The active region exists between the p and n regions. The light emerges from the active side in all the directions when electron hole-pairs ... fig.(c). In this way an LED emits light. This is the principle of operation of LED.

Description : What is photodiode? Draw the symbol and explain operation of photodiode. 

Last Answer : A photodiode is a light detector that converts light into an electrical current. A photodiode is a semi-conductor device, with a p-n junction and an intrinsic layer between p and n layers ... current is independent of reverse bias voltage. Reverse current is mostly depends on the light intensity.

Description : Define resistor and draw symbol of variable resistor.

Last Answer : Resistor: A resistor is an electrical component that limits or regulates the flow of electrical current in an electronic circuit. Symbol of variable resistor:   

Description : Draw & explain operation of phase detector.

Last Answer : In phase detector, the op-Amp basically acts as a zero crossing detector. If a sine wave is applied at the i/p, we get square wave at the op-Amp o/p (at point ... to two channel of the CRO. The time duration between the pulses corresponding to voltages represent the phase between them. 

Description : Analyze the effect of supply voltage on performance of LED as regards current, Lumen output, efficacy and life. 

Last Answer : 1) Effect on Current:- In LED current depends upon supply voltage, if voltage get changes then current also change but this change in current will be control by resistors which are connected in series.  2) ...   4) Effect on Life:- If supply voltage is not stable then life of LED get reduced. 

Description :  Compare the salient features of LED and CFL based on: i] Lamp Efficiency ii] Life span 

Last Answer : Parameter LED CFL Lamp Efficiency  High (more than 70 lumen per watt) Comparatively less (50-60 lumen per watt) Life span (in working hours) 10000 3000

Description : Give the full form of SCADA & HMI.

Last Answer : Full Form of SCADA and HMI:  SCADA:-Supervisory Control and Data Acquisition  HMI :- Human Machine Interface

Description : Draw the block diagram of PLC.

Last Answer : Block diagram of PLC and input/output devices used for PLC Input/output devices - The input module has bank of terminals for physically connecting input devices, like push buttons, limit switches etc. ... is to translate signals from the PLC's CPU into a form that the output device can use.

Description : Draw the block diagram of regulated power supply, explain function of each block and draw waveforms of each stage.

Last Answer : 1. A step down transformer 2. A rectifier 3. A filter 4. A regulator Operation of Regulated Power Supply:- Step Down Transformer:- A step down transformer will ... regulator. A regulator will maintain the output constant even when changes at the input or any other changes occur.

Description : Draw & explain touch plate switch using IC555.

Last Answer : It is construct form monostable multivibrator , when metal plates touch by finger then voltage at pin number 2 goes to below 1/3 Vcc then output of lower comparator becomes high hence flip flop set and ... then output of timer goes low and it low till up to the metal plates touch by finger .

Description : Draw equivalent circuit of alternator.

Last Answer : Equivalent circuit of alternator

Description : State different types of electrical signal and draw all types of waveforms.

Last Answer : Types of electrical signals 1) Sine wave 2) Triangular wave 3) Square wave Waveforms

Description : Draw block diagram of PLL as a FM demodulator. Explain function of each block.

Last Answer : Operation:  The FM signal which is to be demodulated is applied at the input of the PLL.  the PLL is locked to the FM  The error voltage produced at ... using PLL ensures a high Linearity, between the instantaneous input frequency and VCO control voltage (error amplifier output)

Description : Draw symbol & V-I characteristics of (i) LASCR (ii) DIAC (iii) TRIAC

Last Answer : (i) LASCR:  (ii) DIAC:  (iii) TRIAC: 

Description : Draw symbol of NPN and PNP transistors. 

Last Answer : symbol of NPN and PNP transistors

Description : State the procedure for testing of earth pit resistance with necessary diagrams.

Last Answer : Following procedure (Method) for testing of earth pit resistance with necessary diagrams. 1) Earth Tester : i) Three point method ii) Four point method 2) By Potential drop method 3 ... of that earthing pit. In this test the accuracy is less but electrical rods are not required. 

Description : State the procedure for laying / installation of underground cable.  

Last Answer : 1) Direct laying Cable: or Trench laying method: Procedure: * For laying of a cable trench about 1.5m deep and 0.5m wide is made along the cable route. * A ... over. * Cables laid in this manner are usually plain lead covered because troughing affords good mechanical protection. 

Description : State any two advantages of MCB over Fuse. State the standard specifications of MCB available in the market.  

Last Answer : Following advantages of MCB over Fuse: 1. No need of replacement of fuse wire. 2. Manually restore of supply is simple. 3. Fault understanding by visual inspection 4. More safe than fuse The standard specifications of ... 6A, 10A,16A,20A, 25A, 30A, 32A, 40A, 50A, 60A and 63A 6. 250V and 450 v

Description : Explain the suitability of aluminium as an electrical conductor with respect to its mechanical and electrical properties. 

Last Answer : Following are requirements of conductor:- i) High conductivity :  Material should have high conductivity, So that * cross section of conductor (size) reduces, * Copper losses reduces, * So Efficiency ... . Boiling point is 1820°C 9. Specific gravity is 2.7 10. High resistance to corrosion. 

Description : State the type of insulating materials under Class Y and Class B.

Last Answer : The type of insulating materials under Class Y : 1. Cotton  2. Silk 3. Paper 4. Rubber 5. PVC The type of insulating materials under Class B: 1. Backelite 2. Impregnated varnish 3. Mica 4. Fiber glass 5. Asbestos 

Description : State the types of protections provided by MCB. 

Last Answer : The types of protections provided by MCB: 1. MCB provides short circuit protection. 2. MCB provides overload protection

Description : Explain with neat sketch the working principle of MIG.

Last Answer : In metal-arc inert gas welding the Weld area is shielded by an effectively inert atmosphere of argon, helium, carbon dioxide, or various other gas mixtures . The consumable bare Wire is fed automatically ... of the molten-weld puddle. Multiple-weld layers can be deposited at the joint. 

Description : State the applications of TIG welding.

Last Answer : The applications of TIG welding are as follows: 1. Mostly used to weld aluminum and aluminum alloys. 2. It is used to weld stainless steel, carbon base alloy, copper base alloy, nickel base alloy etc. 3. It is used to welding dissimilar metals. 4. It is mostly used in aerospace industries.

Description : State the applications of rolling.

Last Answer : Applications of rolling are as follows: 1. Concrete reinforcing bars. 2. Plates. 3. Wire rods. 4. Sheet and strip. 5. Rails. 6. Piping and tubes. 7. Body panels. 8. Construction materials

Description : Define armature reaction in an alternator. Explain the effect of armature reaction at various P.F. of loads of alternator.

Last Answer : Armature Reaction: The effect of armature flux on main flux is called as armature reaction.  Armature Reaction at Various Power Factors: When armature is loaded, the armature flux modifies ... lagging p.f. For capacitive loads the effect of flux is partly distorting and partly strengthening.

Description : State the modification to be done in dc series motor to work satisfactorily as ac series motor. State applications of ac series motor.

Last Answer : Modifications are necessary in a dc series motor so that it operates satisfactorily on ac supply. The modifications are as follows:  1) AC series motor is built with a few field turns as ... and grinders 5) High speed vacuum cleaners 6) Sewing machines 7) Food processors 8) Drilling machine 

Description : Explain the activities carried out during weekly maintenance of 3 ph. Induction motor. 

Last Answer : Activities Carried out During Weekly Maintenance of 3 ph. Induction Motor:  1) Check belt tension. In cases where this is excessive it should immediately be reduces and in the case of sleeve ... and cooled by oil mist systems its important to check the oil mist flow paths/pressure components.

Description : State the need of automation. 

Last Answer : Need of Automation in Process : * To fulfill the demand of product at right time. * To reduce the human errors and involvement of human being in the process. * For better productivity. * For better ... of process. * For better quality. * For reducing man power. * For reducing cost of product.

Description : Give the expression for ABCD constant of T model.

Last Answer : Expression for ABCD constants of T model: 

Description : State the impact of inductance and resistance on transmission line performance

Last Answer : Impact of inductance on transmission line: 1) It causes IXL drop in transmission line which affects regulation. 2) It is the only parameter which decides power transmission capacity of line i. ... is very small, it causes losses, temperature rise& poor voltage regulation so it cannot be neglected

Description : State the classification of distribution substation. 

Last Answer : The classification of distribution substation. 1. Pole mounted distribution substation 2. Plinth mounted distribution substation 3. Compact/prefabricated distribution substation 4. ... Indoor distribution substation 6. Outdoor distribution substation 7. Mobile distribution substation 

Description : State the needs and benefits of star labelling. 

Last Answer : Needs of star labelling: * Star labelling is meanly required to recognize quality of product * Star labelling is also required to determine life and efficiency of the product. * Star labels ... emission and air pollution will be reduces. 5. Market efficiency and compilation will be improve. 

Description : List the different types of tariff.

Last Answer : Various types of Tariff:-  1) Flat-demand Tariff  2) Simple-demand Tariff or Uniform Tariff  3) Flat-rate Tariff  4) Step-rate Tariff  5) Block-rate Tariff  6) Two-part Tariff  7) Maximum demand Tariff ... c) KW and KVAR Tariff 10) TOD (Time of Day) Tariff 11) TOU ( Time of Usage) Tariff

Description : State the advantages of cogeneration. 

Last Answer : Advantages of co-generation: 1) Co-generation can meet both power & heat requirements. 2) Less cost than conventional generation. 3) Higher system efficiency due to energy wastage is highly ... reduces due to cogeneration plant is located in same premises. 10) It can maintain grid stability 

Description : State the requirements of illumination scheme of shipyard.

Last Answer : Requirements of illumination scheme of shipyard:  1) The shipyard lighting always depends upon the surrounding conditions. e.g. wind pressure, rain fall, location of shipyard from the sea-share etc. ... solar grass lamps, LED-Solar energy lawn lamps, various focus lamps, metal halide lamps etc.

Description : State the various lighting calculations methods and Describe any one of them.

Last Answer : Lighting calculation methods: 1. Lumens or Light flux method 2. Point to point or Inverse Square law method 3. Watts per Square meter method i) Lumens or Light ... is taken according to the illumination desired on an average value considering overall efficiency of the lighting system.

Description : State the different types of outdoor flood lighting and where are they used.

Last Answer : There are three types of projectors used for flood lighting :  a) Narrow beam Projector b) Medium angle Projector c) Wide angle Projector a) Narrow beam Projectors: - Light beam with such ... yards, stadiums, car parking area etc. 3) It is used for illuminating advertisements, boarding's etc.

Description : State the purpose of lighting control. List the different types of dimmer.

Last Answer : Purpose of Lighting Control:- 1. To turn ON or OFF the lamps 2. For dimming: The dimming control permits the adjustment of lighting over a range. 3. For changing the lighting levels ... operated dimmer 6) Triac operated Dimmer 7) PWM (Pulse width modulation) Controlled technique.

Description : Explain the lighting scheme to be designed for each of the following: i) Special ward in hospitals ii) Dentist’s Cabin 

Last Answer : i) Special ward in hospital: For the patients in the wards, lighting should create a cozy and pleasant atmosphere. Lighting in the wards should be planned in such a way that it meets the specific ... we use such as cements and bonding agents that we use to restore your teeth back to health.

Description : Describe the working principle of Thyristor operated dimmer with the help of circuit diagram.

Last Answer : Thyristor operated dimmer: A popular thyristor operated dimmer circuit employ TRIAC-DIAC phase control for low AC power control. During each half-cycle, the capacitor charges through (R1+VR1). When the ... time constant {C (R1+VR1)}. Thus by reducing VR1 the lamp brightness can be increased.

Description : State the selection criterion of the lamp for various purposes.

Last Answer : Selection criterion of the lamp for various purposes:  While selecting a lamp for a particular purpose, the available lamps are compared on the basis of following criteria: * Light output ... such as ballasts * Compatibility with the electrical system * Suitability for the operating environment

Description : Explain the working of Neon sign tube with diagram.

Last Answer : Neon sign tube: The construction & circuit diagram for neon tube is as shown in fig. Basically neon tube is used for advertisement or decoration purpose. The maximum length of tube is ... the HT transformer must be earthed separately. * Caution notice of danger board is required.

Description : Explain the working of HPMV Lamp with neat diagram.

Last Answer : High-pressure Mercury-Vapour Lamp (HPMVL):  Working:  * Whenever 1-ph, 230V, AC Supply is provided to the discharge tube of MVL, initially the current flows from Phase to the choke to ... : The function of power factor improvement capacitor is to improve the power factor from 0.5 to 0.95.

Description : Explain the features of Aquarium lighting. 

Last Answer : 1) The aquarium light depends upon the size of the aquarium tank (Length, width and depth)  2) The aquarium lighting depends upon the all surrounding condition e.g. colour and size of the given ... The aquarium lighting should be economical.  9) The life of the aquarium lighting should be long. 

Description : With the help of N-channel JFET describe the effect of input voltage VGS on output current ID.

Last Answer : Working of N channel FET: * When a voltage is applied between the drain and source with a DC supply (VDD), the electrons flows from source to drain through narrow channel ... where the channel gets completely blocked and the drain current becomes zero is called pinch- off voltage. 

Description : Describe the concept of virtual ground with reference to op-Amp.

Last Answer : Virtual ground concept:-In circuit point A is virtual ground. Figure shows inverting amplifier using op-amp. In this circuit non-inverting terminal is connected to the actual ground. Due to ... zero potential without actually grounding is known as virtual ground concept. Circuit diagram: 

Description : State functions of the following pins of IC555.

Last Answer : 1) Control: - The dc Voltage at this pin is 2/3 Vcc. An external voltage applied to this changes threshold as well as trigger voltage to obtain pulse width modulated output.  2) Trigger: - The ... greater than 2/3 Vcc . When the voltage goes below 1/3 Vcc, output of the timer goes high.

Description : Write applications of each of the following:(i) Fuse (ii) MCB (iii) MCCB.

Last Answer : i) Applications of fuse:  * Used in domestic installations to provide short circuit protection.  * Used in commercial / Industrial installations to provide overload and short circuit protection.  * Used in ...  * Rectifiers panels,  * U.P.S, Electronic equipment,  * Motors,  * Furnaces

Description : What is earthing? Give the importance of earthing.

Last Answer : Meaning of earthing: Connecting the metallic frame of the electrical machines /any electrical equipment body etc. to ground by using wire/conductor is known as earthing.  Importance of Earthing:  ... currents. 5. To provide stable platform for operation of sensitive electronic equipment's. 

Description : Give the function of fuse and switch.

Last Answer : Functions of fuse:  * To break the circuit under fault condition.  * To provide overcurrent protection to the circuit.  * To provide short circuit protection to the circuit.  * To provide ...  * To make the electric circuit manually.  * To break the electric circuit manually.