How do you know the voltage of an LED?
Last Answer : After connecting led to a DC source we can measure the voltage of led by connecting a voltmeter across it. But voltage rating of the led is given by the manufacturers. Or we can ... in the market For more doubts connect with me in linkdin Subrahmanyampampana1997@gmail.com
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156 views
2 answers
asked
Dec 9, 2017
by
anonymous
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.
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106 views
1 answer
asked
May 3, 2020
by
anonymous
How To Make A Red, White And Blue Pinwheel
Last Answer : Materials: Red, white and blue construction paper Scissors Glue stick 1/4 inch dowel Brass tack Directions: Cut one 6-inch square from the red paper and one 6-inch square from the blue paper. ... center of star and then through overlapping tips. Press end of tack onto the side of the dowel.
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7 views
1 answer
Herrings with Red Salsa
Last Answer : Herrings with Red Salsa - serves 4 2 tbsp skimmed milk 2 tsp Dijon mustard 2 large herrings, filletted 2/3 cup rolled oats Salt and pepper to taste Salsa: 1 small red pepper, seeded 4 medium tomatoes 1 ... , then ots to coat. Place on a baking sheet, then bake for 20 minutes. Serve with the salsa.
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4 views
1 answer
asked
Apr 29, 2021
by
anonymous
How to Build a Led Billboard
Last Answer : How to Build a Led Billboard How to Build a LED Billboard LEDs are basically light emitting diodes. They tend to emit light when an electrical power courses through them. A LED billboard is a ... plazas. China is one of the largest competitors in the global market for producing state of art LEDs.
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6 views
1 answer
asked
May 12, 2021
by
anonymous
What are the advantages of LED lamps?
Last Answer : What are the advantages of LED lamps? LED lamps have an advantage over fluorescent lamps in the first place in terms of environmental friendliness. Another reason for using LED lamps is ... advantages. Today, such lamps are used in everyday life, for industrial lighting and street lighting.
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14 views
1 answer
asked
Mar 29, 2021
by
anonymous
Advantages of LED over CFL.
Last Answer : Advantages of LED over CFL. 1) Efficiency: LED bulbs use close to a third of the amount of power CFL bulbs would use to produce the same amount of light. This makes them ... decorative to heavy duty industrial applications. 6) Maintenance: Smooth light and low maintenance compared to CFL
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80 views
1 answer
asked
May 27, 2020
by
anonymous
Draw symbols of zener diode and LED.
Last Answer : Symbol of zener diode : Symbol of LED
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426 views
1 answer
asked
May 16, 2020
by
anonymous
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
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96 views
1 answer
asked
May 3, 2020
by
anonymous
Why the Led Glow in Dc Supply ? Whenever give the Ac Supply What is Affect in Led ?
Last Answer : LEDs consume DC current to produce light; with AC current the LED will only be lit when current flow is in the proper direction. AC applied to an LED will cause it to blink on and off, and at high frequency the LED will appear to be lit continuously.
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84 views
1 answer
asked
Aug 12, 2019
by
anonymous
Describe working principle of LED with diagram.
Last Answer : Constructional Diagram: * Light Emitting Diode (LED) works only in forward bias condition. When Light Emitting Diode (LED) is forward biased, the free electrons from ... gallium arsenide and gallium phosphide the emitted photons have sufficient energy to produce intense visible light.
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3.2k views
4 answers
asked
Jul 24, 2019
by
anonymous
Draw the symbol of LED & photodiode.
Last Answer : Symbol of LED & photodiode
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114 views
1 answer
asked
Jul 10, 2019
by
anonymous
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.
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405 views
2 answers
asked
Sep 4, 2018
by
anonymous
List four applications of LED.
Last Answer : Applications of LED 1.As a power supply status indicator in electronics instruments 2.In traffic light Indicators. 3.In data displaying boards. 4.In medical applications and toys 5.In optical fiber communications 6.Remote controls
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80 views
1 answer
asked
Sep 4, 2018
by
anonymous
Why do dimmable LED lights flicker?
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92 views
0 answers
asked
Mar 10, 2018
by
anonymous
Are ginger haired people a race?
Last Answer : There isn’t such thing as Ginger haired people! I just think it’s very stupid for people to call red heads GINGERS! There is no race in that
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0 views
1 answer
asked
Feb 27
by
anonymous
The SCR would be turned OFF by voltage reversal of applied anode-cathode ac supply frequency of A) 10 kHz B) 10 Hz C) 5 kHz D) 5 Hz
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187 views
0 answers
asked
Jun 18, 2018
by
anonymous
The voltage gains of the amplifier with and without feedback are 20 and 100 respectively. The percentage of negative feedback would be
Last Answer : The voltage gains of the amplifier with and without feedback are 20 and 100 respectively. The percentage of negative feedback would be 4%
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162 views
1 answer
asked
May 3, 2018
by
anonymous
An amplifier has a voltage gain of 120. To reduce distortion, 10% negative feedback is employed. The gain of the amplifier with feedback is (1) 141 (2) 92.3 (3) 9.23 (4) 1.41
Last Answer : An amplifier has a voltage gain of 120. To reduce distortion, 10% negative feedback is employed. The gain of the amplifier with feedback is 9.23
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318 views
1 answer
asked
May 1, 2018
by
anonymous
The voltage gain of a common -source JFET amplifier depends up on its (1) Input impedance (2) Amplification factor (3) Dynamic drain resistance (4) Drain load resistance
Last Answer : B
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1.0k views
3 answers
asked
Apr 30, 2018
by
anonymous
A dc chopper is fed from a constant voltage mains the duty ratio of chopper is progressively increased while the chopper feeds an RL load. The per unit current ripple would (1) increase progressively (2 ... 0.5 and then increase (4) increase to a maximum value at α = 0.5 and then decrease
Last Answer : A dc chopper is fed from a constant voltage mains the duty ratio of chopper is progressively increased while the chopper feeds an RL load. The per unit current ripple would increase to a maximum value at α = 0.5 and then decrease
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526 views
1 answer
asked
Apr 30, 2018
by
anonymous
A voltage source inverter will have better performance if its (1) load inductance is small and source inductance is large. (2) both load and source inductance are small. (3) both load and source inductances are large. (4) load inductance is large and source inductance is small.
Last Answer : A voltage source inverter will have better performance if its load inductance is large and source inductance is small.
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3.6k views
1 answer
asked
Apr 30, 2018
by
anonymous
A voltage source inverter is normally employed when (1) source inductance is large and load inductance is small (2) source inductance is small and load inductance is large (3) both source and load inductance are small (4) both source and load inductance are large
Last Answer : 3
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1.9k views
2 answers
asked
Apr 29, 2018
by
anonymous
The threshold voltage of an n- channel enhancement mode MOSFET is 0.5V when the device is biased at a gate voltage of 3V. Pinch off would be occurs at a drain voltage of (A) 1.5V (B) 2.5V (C) 3.5V (D) 4.5V
Last Answer : The threshold voltage of an n- channel enhancement mode MOSFET is 0.5V when the device is biased at a gate voltage of 3V. Pinch off would be occurs at a drain voltage of 2.5V
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316 views
1 answer
asked
Apr 28, 2018
by
anonymous
Explain the pulse width modulation technique for control of AC output voltage.
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101 views
0 answers
asked
Mar 10, 2018
by
anonymous
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Explain the principle of ON-OFF control and phase control of AC voltage controller with suitable circuit and waveforms.
Last Answer : The integral cycle control (on-off control) and phase angle control are the two types of AC voltage controller. The principle of ON-OFF control: The on-off control is also called an integral cycle ... control. In phase control, the switch is on for some period of each cycle.
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3.5k views
1 answer
asked
Feb 14, 2018
by
anonymous
What is the ripple voltage?
Last Answer : Ripple voltage is the small variations in Dc voltage that remain after filtering in a power supply.
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155 views
3 answers
asked
Dec 9, 2017
by
anonymous
Justify. Power MOSFET is operated at high enough gate source voltage to minimize the conduction losses.
Last Answer : MOSFET is metal oxide field effect transistor. MOSFET is a voltage controlled device. MOSFET is majority carrier device. MOSFET are of two one is n-channel MOSFET and p-channel MOSFET. Gate, ... . Hence, power MOSFET is operated at high enough gate-source voltage to minimize the conduction losses.
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842 views
1 answer
asked
Dec 7, 2017
by
anonymous
Last Answer : Yes, Zener diode is a voltage regulator. Zener diode maintain constant reverse Biased Voltage. If the current is varying then also zener diode maintain constant voltage.
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109 views
1 answer
asked
Sep 13, 2017
by
anonymous
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Last Answer : already answered here is mosfet current controlled device?
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172 views
1 answer
asked
Sep 10, 2017
by
anonymous
What is Voltage Source Inverter (VSI) ?
Last Answer : Voltage Source Inverter (VSI) Inverter is device which converts Direct Current (DC) to Alternating Current (AC). There are two types of inverters one is Voltage source inverter ... VSI consist of two load terminals and three phase VSI consist of three load terminals.
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225 views
1 answer
asked
Aug 9, 2017
by
anonymous
Draw the structural diagram of GTO. Explain briefly the switching behavior of GTO with the help of appropriate voltage and current waveform.
Last Answer : Gate Turn Off Thyristor (GTO) Conventional Thyristor can be turned on with gate terminal but can not turn off from gate terminal. But in case of Gate Turn Off Thyristor (GTO), we can turn it on and off ... subdivided as storage period (Ts), fall period (Tp) and tail period (Tt).
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1.7k views
1 answer
asked
Aug 8, 2017
by
anonymous
Why does surge impedance loading (SIL) increase with increase in voltage level?
Last Answer : Answer: SIL varies as the square of the operating voltage, so SIL increases with increase in voltage level
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25 views
1 answer
Electro-mechanical voltage regulators are generally used in (a) reactors (b) generators (c) transformers (d) all of the above
Last Answer : (b) generators
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11 views
1 answer
When an alternator connected to the bus-bar is shut down the bus-bar voltage will (a) fall (b) rise (c) remain unchanged (d) none of the above
Last Answer : (c) remain unchanged
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18 views
1 answer
The frequency of voltage generated, in case of generators, can be increased by (a) using reactors (b) increasing the load (c) adjusting the governor (d) reducing the terminal voltage (e) none of the above
Last Answer : (c) adjusting the governor
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10 views
1 answer
When the interconnector between two stations has large reactance (a) the transfer of power will take place with voltage fluctuation and noise (b) the transfer of power will take place with least loss ... out of step be¬cause of large angular displacement between the stations (d) none of the above
Last Answer : (c) the stations will fall out of step be¬cause of large angular displacement between the stations
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14 views
1 answer
For transmission of power over a distance of 500 km, the transmission voltage should be in the range (a) 150 to 220 kV (b) 100 to 120 kV (c) 60 to 100 kV (d) 20 to 50 kV
Last Answer : (a) 150 to 220 kV
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41 views
1 answer
Constant voltage transmission entails the following disadvantage (a) large conductor area is required for same power transmission (b) short-circuit current of the system is increased (c) either of the above (d) none of the above
Last Answer : (b) short-circuit current of the system is increased
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12 views
1 answer
In a tap changing transformer, the tappings are provided on (a) primary winding (b) secondary winding (c) high voltage winding (d) any of the above
Last Answer : (b) secondary winding
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51 views
1 answer
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Which of the following equipment, for regulating the voltage in distribution feeder, will be most economical ? (a) Static condenser (b) Synchronous condenser (c) Tap changing transformer (d) Booster transformer
Last Answer : (d) Booster transformer
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19 views
1 answer
For transmission of power over a distance of 200 km, the transmission voltage should be (a) 132 kV (b) 66 kV (c) 33 kV (d) 11 kV
Last Answer : (a) 132 kV
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54 views
1 answer
The voltage drop, for constant voltage transmission is compensated by installing (a) inductors (b) capacitors (c) synchronous motors (d) all of above (e) none of the above
Last Answer : (c) synchronous motors
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13 views
1 answer
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By which of the following a bus-bar is rated ? (a) Current only (b) Current and voltage (c) Current, voltage and frequency (d) Current, voltage, frequency and short time current
Last Answer : (d) Current, voltage, frequency and short time current
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16 views
1 answer
Transmission voltage of ll kV is normally used for distances upto (a) 20—25 km (b) 40—50 km (c) 60—70 km (d) 80—100 km
Last Answer : (a) 20—25 km
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16 views
1 answer
The power transmitted will be maximum when (a) corona losses are minimum (b) reactance is high (c) sending end voltage is more (d) receiving end voltage is more
Last Answer : (c) sending end voltage is more
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32 views
1 answer
Which of the following is usually not the generating voltage ? (a) 6.6 kV (b) 8.8 kV (c) 11 kV (d) 13.2 kV
Last Answer : (b) 8.8 kV
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33 views
1 answer
As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only (a) 31.25 percent of copper (b) 33.3 percent of copper (c) 66.7 percent of copper (d) 125 percent of copper
Last Answer : (a) 31.25 percent of copper
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18 views
1 answer
Transmitted power remaining the same, if supply voltage of a D.C. 2-wire feeder is increased 100 percent, saving in copper is (a) 25 percent (b) 50 percent (c) 75 percent (d) 100 percent
Last Answer : (b) 50 percent
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38 views
1 answer
In a D.C. 3-wire distribution system, balancer fields are cross-connected in order to (a) boost the generated voltage (b) balance loads on both sides of the neutral (c) make both machine^ run as unloaded motors (d) equalize voltages on the positive and negative outers
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