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BJT Control Device
Why BJT is called current control device?
tiya18leo
- Oct 8th, 2009
Because the input current of the transistor controls the output current, for example in CE configuration base current Ib controls the output current Ic.
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Breaker Capacity
Why making capacity of the circuit breaker is higher than breaking capacity?
rajashekharreddy
- Dec 4th, 2009
Making capacity is the max fault current it can carry during closing of breaker, e.g. You are closing a breaker on fault. The making capacity is always higher because it is expressed in peak value not rms, and also because of the DC offset, voltage and PF while closing
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Potential Transformers
What are potential transformers?
bharati.anil
- Oct 20th, 2009
Potential Transformer is designed for monitoring single-phase and three-phase power line voltages in power metering applications. The primary terminals can be connected either in line-to-line or in li...
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Conductor Resistivity
When a small amount of Cu is added to a Ni conductor, then the?a) Resistivity of Ni will decrease at all temperatures because Cu is better conductor than Nib) Residual resistivity of Ni at low temperatures will increase as Cu atoms acts as defect centersc) Resistivity of Ni will increase at all temperatures as Cu destroys the periodicity of Ni and acts as defectsd) Resistivity of Ni remains unaltered...
Lokesh M
- Jan 3rd, 2013
Answer is C. If a small amount of Cu is added to Ni conductor, then resistivity of Ni will increase at all temperatures as Cu destroys the periodicity of Ni and acts as defects. According to Matthies...
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Binary to Gray Code
Ist convert 8 bit binary to gray code using EXOR ICs and again convert gray to binary code
vicky.bishnoi
- Jun 30th, 2009
Take XOR of binary no. starting from right with the next bit. Add 0 as leftmost bit to get answereg. ?111=7gray code 0 xor 1,1 xor 1, 1 xor 1 i.e. 100 ans.
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Knee Point Voltage
How to calculate knee point voltage? Describe its purpose for differential protection.
vikash798
- Sep 3rd, 2010
10 % increase in voltage gives you 50 % increase in excitation current is called knee point voltage. To measure this first demagnetise the CT and apply voltage gradually from secondary keeping primary winding open circuited. while doing this above phenomeneo will be observed.
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TV Aspect Ratio
Why the aspect ratio of TV video display is 4:3 or 16:9? Why not it is any other?
kumar praveen bodu
- Mar 23rd, 2010
In TV it is conviniance to appear the object in horizontal manner, so it is better to fix the horizontal lengh more than vertical. 4:3 and 16:9 are the suitable lengths for human naked eye.
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Regulators without Filters
What problem arise if we use regulators without/before filters?
jayakumarau
- Nov 15th, 2009
Filters are used for reducing ripples. A regulator output will be having many ripples. So filters are used in a circuit for conversion of pulsating AC to DC
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Signal Processing
Why do we convert Frequency Domain to Laplace Domain?
RZara
- Nov 24th, 2009
Frequency domain ----> deals with jw Laplace domain ----> deals with s, but s = (sigma) + ( jw )so with sigma = 0, laplace domain and frequency domain are the same. We convert time domain to eit...
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LED's for Rectification
Why cannot we use LED's for rectification purpose?Can we get light when the circuit is working?
maxandrean
- Jul 5th, 2010
LED is not designed for resctifier purpose, even though theoritically it can be use, but the nature of the current flow capacity of LED is not suitable to be used as reactifier. LED works in micro Amp...
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Q-METER
Q-Meter works on which principal?
kapilgupta.mnit
- Mar 10th, 2010
A direct-reading instrument which measures the Q of an electric circuit at radio frequencies by determining the ratio of inductance to resistance, and which has also been developed to measure many other quantities. Also known as quality-factor meter.
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Aviation Industry Radio Transmission Frequency
Why is 400 Hz used for flight instruments and Radio Transmission System in Aviation Industry universally?
lakshmyranjith
- Sep 5th, 2010
You need some sort of AC for power transmission and distribution inside of aircraft. Power companies use 50/60Hz because any higher frequency results in excessive inductive and capacitive losses, give...
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Antenna Length
Why length of antenna is taken as one half of wavelength or one fourth of wavelength? Why not one eighth or one sixteenth?
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GSM Interfaces
What are the interfaces used in GSM?
vin18
- May 23rd, 2011
The different interfaces used in GSM listed as follows: 1. GSM radio air interface: This is the interface between MS and BTSs. 2. Abis interface: The one connecting the BTS to a BSC is known as Abis...
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Excitation Table
What is the use of excitation table in digital electronics?
vinit.slim.shady
- Jan 10th, 2011
Excitation table is required when we want to design a state machine from the truth table of any of the flip flops used.
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Device Frequence
How will you determine what frequency the device has without using oscilloscope?
Er.Anju
- Dec 21st, 2010
The frequency of a device can also be calculated by the method below:- Speed of light (c) =299,792,458 m/s. Planck constant (h) =4.13566733E'15 eV s (1E-15 denotes "10 in power -15") Frequency(Hz) = ...
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H-parameter
What is hybrid parameter
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Waveforms Applications
what are the application of different waveforms ? Explain how they are used in real time ?
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Pn junction
If there is the level of impurity in p-type & n-type semiconductor of pn junction diode is different then what effect on depletion?
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