Define photo resistor. State its symbol and its two applications. 

1 Answer

Answer :

Definition: It is a type of semiconductor whose electrical resistance decreases as the intensity of incident light increases.

Applications: i) It is used for automatic lighting control. ii)It is used in the street light control. iii)It is used in photocopy machine to control density of toner. iv)It is used in security alarm. v)It is used in camera for Exposure meter.

Related questions

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 : State working principle of photo diode. List out its three applications.

Last Answer : Diagram of photo diode :  Working principle of photo diode :  When photons of energy greater than 1.1 eV hit the diode, electron-hole pairs are created. The ... Smoke detector, Optical communication devices, Position sensors, Bar code scanners, Automotive devices, Surveying instruments

Description : Define photo conductive polymer. Give its examples and applications.

Last Answer : Photo conductive polymer: These are the polymers which conduct electricity only in the presence of light. Examples: i) PVK or poly(N-vinyl carbazole ) ii) Poly (vinylpyrene),iii) poly(2- ... resistors are often used include camera light meters, street lights, clock radios and infrared detectors.  

Description : State applications each of photo-diode and 7-segment display.

Last Answer : Applications of photo-diode:- 1) In cameras 2) In fiber optic receiver 3) in object counting system  Applications of 7-segmet display 1) In calculators 2) In Wrist watches

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

Last Answer : 1) Push Button  It is used in start-stop control circuit 2) Selector Switch : It is used to select one input out of many,  3) Solenoid valve: is used to control flow of fluid such as air, pressurized oil.  4) Limit switch: It is used to detect presence of object

Description : Which of the listed electrical devices is represented by the symbol shown in the illustration? EL-0055 A. Fixed resistance resistor B. Coil with magnetic core C. DC motor or generator shunt field D. Transformer

Last Answer : Answer: D

Description : What is represented by the electric symbol figure 'D' in the illustration? EL-0005 A. Fuse B. Plug-in contact resistor C. Variable capacitor D. Electrolytic capacitor

Last Answer : Answer: A

Description : Draw the symbol of i) Iron core inductor ii) variable capacitor iii) resistor iv) Ferrite core inductor

Last Answer :  Iron core inductor:  Ferrite core inductor:  

Description : State the applications and specification of (i) Resistor (ii) Capacitor (iii)Inductor

Last Answer : Application of resistor: 1.Resistors are used in high frequency instrument. 2.Resistor is used in power control circuit. 3.It is used in DC power supplies. 4.Resistors are used ... DC Current  3.Electromagnetic Interference (EMI)  4.Magnetic Saturation Flux Density  5.Curie Temperature 

Description : The arrow drawn through the resistor shown in the illustration indicates that it is _____________. EL-0086 A. for use in low power applications B. a carbon composition type C. a wire-wound type D. one whose resistance is variable

Last Answer : Answer: D

Description : List any two applications of photo diode and IRLED 

Last Answer : Photodiode 1. In the cameras for sensing the light intensity. 2. In CD players. 3. In the fiber optic receiver. 4. As photo (light) detector. 5. In light intensity meters. 6. In the ... shaft encoders 4. As a light source in optical fiber system 5. In the burglar alarm system.

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

Last Answer : i) Ideal voltage source: A voltage source whose terminal voltage always remains constant for all values of output current, is known as an ideal voltage source. It has zero internal resistance.  ... the voltage drop in the internal resistance.  Symbol of Practical Voltage Source: 

Description : (a) Define permeability. (b) Define MMF. (c) Define form factor of an alternating quantity. (d) Define frequency and time period of an alternating quality. (e) Define transformation ratio of transformer. ... and state the meaning of each term used. (g) Give two applications of single phase motors. 

Last Answer : Permeability : It is the ability of a magnetic/Non magnetic material to allow setting up of flux in it.  MMF : The magneto motive force (MMF) is the force required to setup flux in a magnetic / ... applications of single phase motors : Water pumps, ceiling fan, lathe machine

Description : Define ADC and DAC. Write two applications of each.

Last Answer : ADC An analog to digital converter (ADC), converts any analog signal into quantifiable data, which makes it easier to process and store, as well as more accurate and reliable by ... signal, hence any analog circuit can work with digital system Application - Microcontroller, washing machine

Description : Define Isotopes. Give two applications of carbon isotopes. 

Last Answer : Isotopes: The different atoms of the same elements having same atomic number but different atomic mass number are called isotopes.  Applications of Carbon isotopes :   1. C 12 being most ... is used to determine the age of carbon containing materials which are up to 60,000 years old.

Last Answer : Req= (1/1200 +1/560 + 1/2.1)^-1        = 2.1 ohms RT= 2.1 + 7.8      = 9.9 ohms IT = V/R = 24/9.9                = 2.4 A Veq= R I =  2.1 2 ... 7.8         = 12.096 w                 = 44.928 w _________________________________________ By: Ellis-Junior Kamatjipose [email protected]

Description : Which of the following is NOT a non-linear resistor? A) Varistor B) Precision resistor C) NTC thermistor D) PTC thermistor 

Last Answer : Which of the following is NOT a non-linear resistor? A) Varistor B) Precision resistor C) NTC thermistor D) PTC thermistor 

Description :  A resistor in which the resistance changes exponentially with change in temperature is called as A) Potentiometer B) Phototransistor C) Varactor D) Thermistor 

Last Answer :  A resistor in which the resistance changes exponentially with change in temperature is called as Thermistor 

Description : The colour bands on a carbon composition resistor occur in the sequence: yellow, violet, yellow and silver. Its resistance is  (a) 470 KΩ ± 47 KΩ (b) 470 KΩ ± 23.5 % (c) 47 KΩ ± 10 % (d) 47 KΩ ± 5 %

Last Answer : The colour bands on a carbon composition resistor occur in the sequence: yellow, violet, yellow and silver. Its resistance is 47 KΩ ± 10 %

Description : The resistance value of a carbon resistor having Orange, Red, Brown and Golden color bands is

Last Answer : The resistance value of a carbon resistor having Orange, Red, Brown and Golden color bands is 320 Ω ± 5%

Description : The gold color code in a resistor indicates a tolerance of

Last Answer : The gold color code in a resistor indicates a tolerance of 5%

Description : A 1000Ohm, 1 Watt resistor can safely pass a current of

Last Answer : A 1000 Ohm, 1 Watt resistor can safely pass a current of 30 mA

Description : The four stripes of a resistor are yellow-violet-orange-gold. The value of resistor should be A. 470 ohms ± 5 % B. 47 kilo ohm ± 5% C. 47 mega ohms ± 5% D. 4700 ohms ± 10%. 

Last Answer : The four stripes of a resistor are yellow-violet-orange-gold. The value of resistor should be 47 kilo ohm ± 5%

Description : A resistor with the color coded value of 1000 ohms and ± 10% tolerance can have an actual resistance between ________. A. 990 ohm and 1010 ohm B. 900 ohm and 1100 ohm C. 1000 ohm and 1100 ohm D. 900 ohm and 1000 ohm. 

Last Answer : A resistor with the color coded value of 1000 ohms and ± 10% tolerance can have an actual resistance between 900 ohm and 1100 ohm.

Description : Which resistor will be physically larger in size? A. 10 ohm, 50 W B. 100 ohm, 10 W C. 1 kohm, 1 W D. 10 Mohm, 1/ 2 W. 

Last Answer : 10 ohm, 50 W resistor will be physically larger in size.

Description : In a series RC circuit, 12 V (rms) is measured across.the resistor and 15 V (rms) is measured across the capacitor. The value of rms source voltage is: A. 3 V B. 27 V C. 19.2 V D. 1.9 V

Last Answer : In a series RC circuit, 12 V (rms) is measured across.the resistor and 15 V (rms) is measured across the capacitor. The value of rms source voltage is: 19.2 V

Description : Pointer of an analog ohmmeter reading close to zero, indicates the resistor being measured is: A. overheated B. shorted C. open D. reversed

Last Answer : Pointer of an analog ohmmeter reading close to zero, indicates the resistor being measured is: shorted

Description : When an additional resistor is connected across an existing parallel circuit, the total resistance: A. remains the same B. decreases by the value of the added resistor C. increases by the value of the added resistor D. decreases

Last Answer : When an additional resistor is connected across an existing parallel circuit, the total resistance: decreases

Description : The voltage induced across a certain coil is 200 mV. A 1200 resistor is connected to the coil terminals. The induced current will be: A. 1.7 mA B. 16 mA C. 12 mA D. 120 mA

Last Answer : The voltage induced across a certain coil is 200 mV. A 1200 resistor is connected to the coil terminals. The induced current will be: 1.7 mA

Description : The amount of current in a resistor needs to be changed from 120 mA to 160 mA by changing the 24 V source, the new voltage will be: A. 8 V B. 320 V C. 3.2 V D. 32 V

Last Answer : The amount of current in a resistor needs to be changed from 120 mA to 160 mA by changing the 24 V source, the new voltage will be: 32 V

Description : If the rms voltage drop across a 15 kilt resistor is 16 V, the peak current through the resistor is : -  a) 15 mA b) 1.5 mA c) 10 mA d) 1 mA

Last Answer : If the rms voltage drop across a 15 kilt resistor is 16 V, the peak current through the resistor is : - 1.5 mA

Description : Three resistors of 4 Ω, 6 Ω and 9 Ω are connected in parallel. Which resistor consumes the maximum power?  (A) 4 Ω (B) 6 Ω (C) 9 Ω (D) 17 Ω

Last Answer : (c) 9 ohm

Last Answer : A metal resistor has resistance of 10 ohm at 0°C and 11 ohms at 160°C, the temperature coefficient is 0.000625 /°C.

Last Answer : The noise generated by a resistor depends upon its operating temperature.

Last Answer : If R, L and C are the parameters of a resistor then the condition for the resistor to be non-inductive is L = CR2 .

Description : What are the color codes on a resistor?

Last Answer : black   yellow   gold    red     green     blue

Description : Define Inductor. Draw its symbol. 

Last Answer : An inductor is a passive electronic component that stores energy in the form of a magnetic field  

Description : Describe the process of photo emission. State the application of photo emission in electronic components

Last Answer : Process of Photoemission:when light of appropriate frequency and intensity is incident upon a surface of certain materials,the energy of light is given to electrons to leave the surface of metal ... photo tubes are used in door openers,counters, position and temperature control and colour analysis 

Description : Define the terms: i) Photo conductive polymers ii) Liquid crystal polymers 

Last Answer : i) Photo conductive polymers: These are the polymers which conduct electricity only in the presence of light.  ii) Liquid crystal polymers: These are a class of aromatic polyester polymers. These polymers have tendency to align their chains parallel over a long distance from their melt or solution.

Description : The % symbol has a special use in a print statement. Define How would you place this character as part of the output on the screen?

Last Answer : You can do this by using %% in the printf statement. For example, you can write printf(“10%%”) to have the output appear as 10% on the screen.

Description : Consider a discrete memoryless channel and assume that H(x) is the amount of information per symbol at the input of the channel; H(y) is the amount of information per symbol at the output of the channel; H(x|y) is the amount of uncertainty ... (H(x) - H(x|y))]  p(x) (D) max H(x|y)  p(x)

Last Answer : (D) max H(x|y)   p(x)

Description : Define multiplexer. Draw logical symbol of 4:1 multiplexer with truth table and output logical equation

Last Answer : Multiplexer - it is a combinational circuit which selects one input from several inputs and connects it to the output.  It is a circuit which has N-input and single output is called as multiplexer.

Description : Define counter. State four applications of counter.

Last Answer : Counter - The circuit which counts number of clock pulses is called as counter. Applications - Processor Real time clock Calculator Batch counter

Description : While performing an experiment to study the dependence of current on the potential difference across two ends of the resistor, a student keeps the circuit closed for a long time to measure the current and potential difference. State how the resistance of the resistor will be affected?

Last Answer : Answer. When the circuit is closed for a long time, the flow of current will be in excess which causes unwanted heating in the resistor and changes the value of resistance.

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 : State the concept of continuous wave RADAR. Sketch its block diagram. State its any two applications.

Last Answer : Concept- Transmission is continuous here, the circulator is used to provide isolation between the transmitter and the receiver. Since transmission is continuous, it would be pointless to use a ... It is used to measurement of relative velocity to distinguish moving target from stationary objects 

Description : State the working principle of gears and give its applications.

Last Answer : Working Principle:  Gears are mechanical elements which transmit motion by means of successively engaging teeth.  Gears are used to transmit motion from one shaft to another or between ... Agricultural equipment.  Industrial construction.  Mining equipment.  Automotive equipment.

Description : Describe super conductivity. State its applications.

Last Answer : Superconductivity is a phenomenon of exactly zero electrical resistance.  Superconductivity is a quantum mechanical phenomenon. It is characterized by the Meissner effect  The electrical ... nano wire single-photon detector Railgun and Coilgun magnets Electric motors and generators

Description : State working principle of column type load cell and state its any four applications.

Last Answer : Load cell is an elastic member as the primary transducer and strain gauge is the secondary transducer. When this combination is used, it is called load cell. In this case an axial compressive load causes a negative ... . 3. It is used for weighing 4. It is used to measure torque force.

Description : Explain why LVDT gives a residual output at null position. State its 2 applications.

Last Answer : LVDT : Residual voltage may be on account of I/P supply voltage and also due to harmonics produced in the o/p voltage on account of use of iron core.  OR  An incomplete magnetic ... pressure is converted into a voltage. In these applications the high sensitivity of LVDTs is a major attraction.