51 views
by
What is photodiode? Draw the symbol and explain operation of photodiode. 

1 Answer

0 votes
by

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. It produces photocurrent by generating electron-hole pairs, due to the absorption of light in the depletion region. The photocurrent thus generated is proportional to the absorbed light intensity. 

Symbol of Photodiode

image

Operation:

image

1. When external light energy is supplied to the p-n junction photodiode, the valence electrons in the depletion region gains energy. 2. If the light energy applied to the photodiode is greater the band-gap of semiconductor material, the valence electrons gain enough energy and break bonding with the parent atom. The valence electron which breaks bonding with the parent atom will become free electron. Free electrons moves freely from one place to another place by carrying the electric current. 3. When the valence electron leave the valence shell an empty space is created in the valence shell at which valence electron left. This empty space in the valence shell is called a hole. Thus, both free electrons and holes are generated as pairs. The mechanism of generating electron-hole pair by using light energy is known as the inner photoelectric effect. 4. Mostly free electrons move towards the n region. When the free electrons reaches n region, they are attracted towards the positive terminals of the battery. In the similar way, holes move in opposite direction. 5. The strong depletion region electric field and the external electric field increase the drift velocity of the free electrons. Because of this high drift velocity, the minority carriers (free electrons and holes) generated in the depletion region will cross the p-n junction before they recombine with atoms. As a result, the minority carrier current increases. 6. When no light is applied to the reverse bias photodiode, it carries a small reverse current due to external voltage. This small electric current under the absence of light is called dark current. It is denoted by I λ. 7. In a photodiode, reverse current is independent of reverse bias voltage. Reverse current is mostly depends on the light intensity.

Related questions

1 answer 12 views

Draw the symbol of LED & photodiode. 

asked 6 days ago in Elements of Electronics by Shimroz123
2 answers 29 views

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

asked Sep 4, 2018 by Shimroz123
1 answer 18 views

Draw diagram of class A push-pull amplifier and explain its operation. 

asked Sep 5, 2018 by Shimroz123
1 answer 49 views

Draw the single stage RC coupled amplifier circuit and explain its’s operation.

asked Sep 4, 2018 by Shimroz123
0 answers 57 views

What is the symbol of a capacitor?

asked Mar 15, 2018 in Electronics Engineering by Quiz
0 answers 12 views

What is the symbol of acceleration?

asked Mar 15, 2018 in Electrical Machine by Quiz
1 answer 110 views

Explain the series and parallel operation of MOSFET. Which is suitable and why?

asked Sep 15, 2017 in Unit 1 by Quiz
0 answers 44 views

What is the symbol for AC power?

asked Mar 11, 2018 in Electrical Engineering by Quiz
0 answers 392 views

Enlist the different modes of operation of electronic counters and explain any two modes in details.

asked Mar 2, 2018 in Digital Instrumentation by Quiz
1 answer 19 views

Draw and explain RC phase shift Oscillator.

asked Sep 4, 2018 by Shimroz123
1 answer 15 views

Electrical quantities (symbol and basic unit)

asked Jun 29 by Shimroz123
1 answer 5 views

Explain the operation of advanced gas cooled reactor.

asked Sep 7, 2018 by Shimroz123
0 answers 39 views

Explain the basic operation of an oscilloscope with necessary diagram for each section in detail.

asked Mar 2, 2018 in Digital Instrumentation by Quiz
1 answer 93 views

Also, highlight the problem faced during parallel operation.

asked Sep 15, 2017 in Unit 1 by Quiz
1 answer 18 views

The operation of a ramp type Digital Voltmeter is based on the principle of (A) Voltage-to-current conversion. (B) Voltage-to-time conversion. (C) Current-to-time conversion. (D) Current-to-frequency conversion.

asked Apr 28, 2018 in Digital Instrumentation by Shimroz123
1 answer 72 views

What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage:  (A) Eddy Current and Hysteresis losses will be excessive  (B) Current will be too much high  (C) Transformer may start to smoke and burn  (D) No effect

asked May 8, 2018 in Electrical Engineering by Shimroz123
1 answer 32 views

Classify magnetic materials and explain in brief.

asked Sep 4, 2018 by Shimroz123
1 answer 156 views

Explain hysteresis loss, eddy current loss and skin effect limitations with reference to magnetic material.

asked Feb 16, 2018 in Unit 3 by Quiz
1 answer 26 views

An additional condition for parallel operation of three-phase transformers over single-phase transformers is that

asked Apr 29, 2018 in Power Electronics by Shimroz123
1 answer 15 views

Describe the operation of N channel enhancement type MOSFET with diagram.

asked Sep 5, 2018 by Shimroz123
1 answer 55 views

Which of the following thyristors can be used for high frequency of operation? A) TRIAC B) DIAC C) SCR D) GTO 

asked Jun 18, 2018 in Thyristor by Shimroz123
1 answer 24 views

Describe the basic SHA operation with the help of its four mode specifications.

asked Mar 2, 2018 in Digital Instrumentation by Quiz
1 answer 7 views

What is encoder? Draw and explain an optical encoder operation for rotary motion measurement.

asked Sep 13, 2018 by Shimroz123
1 answer 6 views

Describe principle of operation of Doppler type ultrasonic flow meter with diagram. 

asked Sep 8, 2018 by Shimroz123
1 answer 11 views

Describe operation of N-channel JFET

asked Sep 5, 2018 by Shimroz123
1 answer 188 views

parallel operation of MOSFET can be done more easily as compared to thyristor. why?

asked Dec 7, 2017 in Unit 1 by Quiz
1 answer 133 views

Four Quadrant Operation Of DC Motor

asked Aug 9, 2017 in Electrical Machine by Zeeshan
1 answer 30 views

With neat diagram explain calibration of energy meter by direct loading method.

asked Sep 6, 2018 by Shimroz123
0 answers 11 views

Explain why potential difference is necessary to produce current in a circuit.

asked Jun 29 by Shimroz123
1 answer 131 views

List the different errors in wattmeter & explain compensation for it.

asked Sep 5, 2018 by Shimroz123
1 answer 37 views

A four -quadrant operation requires two full converters connected in  (1) Series (3) Back to back (2) Parallel (4) Series Cascade

asked Apr 30, 2018 in Power Electronics by Shimroz123
1 answer 58 views

Explain three phase half wave controller or three phase unidirectional controller.

asked Mar 8, 2018 in Unit 6 by Quiz
1 answer 71 views

Explain three phase full wave controller.

asked Feb 14, 2018 in Unit 6 by Quiz
1 answer 169 views

Explain cycloconverter and its types.

asked Feb 13, 2018 in Unit 6 by Quiz
1 answer 16 views

Draw and explain the operation of pressure transducer having diaphragm as a primary sensor and four strain gauges as secondary sensors.

asked Sep 13, 2018 by Shimroz123
1 answer 4 views

Draw the symbol, logic expression and truth table of NOR gate.

asked 6 days ago in Elements of Electronics by Shimroz123
1 answer 10 views

Draw the symbol and state the applications of : 1) Push button switch 2) Selector switch 3) Solenoid valve 4) Limit switch

asked Sep 2, 2018 by Shimroz123
1 answer 4 views

Define 'Ideal voltage source' and 'Practical voltage source'. Draw the symbol for each.

asked Sep 4, 2018 by Shimroz123
1 answer 4 views

Draw the block diagram of regulated DC power supply and explain the function of each block. 

asked 6 days ago in Elements of Electronics by Shimroz123
1 answer 7 views

Explain Center-tapped full wave rectifier with the help of circuit diagram and draw input output waveforms. 

asked 6 days ago in Elements of Electronics by Shimroz123
1 answer 10 views

Draw and explain the measurement of torque using Torque Cell

asked Sep 13, 2018 by Shimroz123
1 answer 2 views

Draw and explain the working of Schmitt trigger.

asked Sep 13, 2018 by Shimroz123
1 answer 17 views

Draw and explain the working principle of turbine type flow meter. Mention its Application area.

asked Sep 13, 2018 by Shimroz123
1 answer 23 views

Draw and explain the response of first order and second order instruments to the step input.

asked Sep 13, 2018 by Shimroz123
1 answer 20 views

Draw the diagram of zero crossing detector using op-amp and explain its working.

asked Sep 12, 2018 by Shimroz123

Welcome to electronics2electrical.com here you can ask questions related to electrical, electronics, mechanical, telecommunication, instrumentation, computer, mathematics, physics etc.
Be respectful to all the members. Do not copy and paste the answers from other websites which have copyright content. While asking question give full details about it.

Categories

Most popular tags

power motor dc circuit transformer voltage current used system phase resistance factor synchronous load ac energy induction electric generator series frequency between speed capacitor use electrical meter line difference control type mosfet transmission magnetic plant high single instrument bjt unit source advantages function diode and machine winding field define torque parallel amplifier supply shunt thyristor motors electricity arduino maximum time relay armature problem value on transformers types coil diagram state flow ratio material three formula starting direction theorem method emf operating efficiency digital wave microprocessor test instruments inductance loss measure operation connected signal low applications effect single-phase network temperature working constant losses different law wattmeter measuring compare controlled breaker drive device logic rc full switch flux wire resistivity disadvantages free of materials machines angle force converter conductor transistor gain open protection scr core measurement number bridge principle generators reactance circuits negative the friction iron loop short pole battery conservation steam resistors hysteresis computer using analog lines secondary station gate a rectifier inverter linear induced relays nuclear capacitance basic characteristics design direct work rotor electronics ammeter forces diesel damping rlc connection factors capacitors minimum insulation moving regulation running self systems air fault range main stability quality starter igbt eddy alternator ideal rl average 3-phase plants arc thermal error fuzzy biasing dielectric pressure balanced superposition errors copper rotation feedback impedance measured electronic electrons charge inductive transfer explain start off back curve over solar is three-phase tariff locomotive peak bias zener engineering commutator surge conductors rating universal potentiometer density permanent mechanical transducer capacity memory adc excitation two fuse pure harmonics application semiconductor inductor internal pmmc reaction welding resonance traction permeability breakers rms designed electromagnetic si generation brushes switching capacitive shaded rate 1 distribution resistor methods delta star oscillator reluctance simplification algebra 8085 boolean weston dynamometer insulating strength installation definition fuel heating earth units
...