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Electronics Engineering
Electronics Engineering is a branch of engineering that deals with practical applications of electronic components, devices, systems, or equipment. Electronics are devices that operate on low voltage sources, as in electron tubes, transistors, integrated circuits, and printed circuit boards and use electricity as part of its driving force.
24,372 Questions
What is the current carrying capacity of 120 sq mm copper conductor?
1 sq..mm have max. capacity is 10 ampere if these are of copper approximately than 120 sq..mm having current carrying capacity is 1200 ampere
How much resistance allows an impressed voltage of 6 V to produce a current of 0.006 a?
R=V/i
That is 1000 ohm.
Semiconductors: When temperature increases, more electrons jump to conduction band from valance bond. Hence resistance decreases.
Metals: Already plenty of electrons are there in conduction band. When temperature increases, the electrons in conduction band of metal vibrate and collide each other during their journey. Hence the the resistance of metal increases with increase of temperature.
S.Lakshminarayana
How emf is induced in dc motor?
In brief,in a 3 phase SQIM,there are 3 windings per pole in the stator physically 120 degree apart,each of which is fed from per phase of a balanced 3 phase ac supply.As the magnetic field due to current in each winding varies with time as the current is alternating,the resultant field will be found to keep on changing its direction with time in a circular locus,magnitude being constant because of this setup which can be shown mathematically.Thus a rotating flux of constant mag links the rotor which induces an emf in the rotor,though initially both rotor & stator are static.
Another Answer
A three-phase induction motor is, essentially, a transformer. The 'primary' windings being the stator's field windings, and the 'secondary' winding being the bars of the rotor. For this reason, induction motors are often termed 'rotary transformers'. So emfs are induced into the bars by 'transformer action'.
Unlike a 'static' transformer, however, the secondary voltages and the frequencies of the voltages vary with the speed of the rotor.
Why do electronic devices have a short working life?
Most devices, including the Electronic ones, will eventually wear out. The fact that Electronic Devices do not seem to have moving parts ignores the fact that Electricity is the main moving part in the device. The more complex the device then the more things in it that do wear out or break faster
Why was the coloured tv invented?
The worlds first colour television broadcast took place on January 1st 1954.
Actually, not quite the question. Colour television (using a rotating disc fitted with coloured filters) was demonstrated by John Logie Baird to RCA in 1939. His first 'proper' colour television system was demonstrated in 1944.
Voltage dividers are used in a linear circuit to separate the input voltage into a small portion known as the output voltage. It is commonly used to get a low voltage signal equal to the voltage being measured.
Can we use a DC source with an inductor?
Yes, an inductor allows DC to pass through it.
An inductor resists a change in current, proportional to inductance and voltage. At equilibirum, an ideal inductor has zero impedance.
The differential equation for an inductor is di/dt = v / l
Is Voltage the same all parts of a series circuit?
Voltage is an electrical force or pressure that causes current to flow in a circuit. It is an additive in a series circuit.
The higher voltage source forces current backwards into the lower voltage source, which can damage it or even cause it to explode.
The load current will lag the supply voltage by an angle called a 'phase angle', determined by the values of resistance and inductive reactance. The magnitude of the load current will be determined by the impedance of the circuit, which is the vector sum of the resistance and inductive reactance.
Why the resistance of a capacitor is infinite when measures with an ohmmeter?
The typical ohmmeter measures DC resistance by providing DC current and measuring the voltage drop accross the resistor. By definition, the 'ideal' capacitor is an open circuit to DC current and voltage. By definition, an open circuit has infinite resistance.
Of course, real-world capacitors are not ideal. They have a very high parallel leakage resistance and a very small series resistance. And, different meters can measure different ranges of resistance. So, you may not get an infinite/overload measurement on some capacitors with some meters. You may get a very high resistance instead. If so, you are not really measuring the resistance of the 'capacitor', but rather that of the imperfections in the component manufactured to be a capacitor.
ANSWER: The ohmmeter battery will charge the capacitor in 5 time RC after that it quirts there is no more current flow. Any body that claim to be able to check resistance of a capacitor i just a wannabe
What device is used to increase or decrease the voltage of an alternating current?
A transformer is the device used to increase or decrease the voltage of alternating current (AC) This is done through a process referred to as inducing.
It's operation is based on the fact that electricity produces a magnetic field around itself. By placing 2 coils of cable beside each other, the magnetic field of one coil will induce a voltage in the other coil.
What is the charging time on a 9.6 volt battery?
No, not unless it has a voltage or current regulator or series resistance to limit the current (built in somewhere).
Why thermionic valve or vacuum tube are evacuated?
because if it was heated in open air it would burn up
How do you design a half-adder using NOR gate?
Use 4 NOR gates.
For the 1st NOR gate, inputs should be x' and y
For the 2nd NOR gate,inputs should be y' and x
The outputs of NOR 1 and NOR 2 are taken as inputs of NOR gate 3
The output of NOR 3 is the complemented form of the output required, so, just complement the output of NOR gate 3 with another NOR gate and Viola!, you have your HALF ADDER OUTPUT
PS:I have used a double rail logic, where both x:x' and y:y' are available
What is single tuned voltage amplifier?
it is a circuit consisting of a tuned circuit with a capacitor in parallel with inductor and it is connected to collector terminal in common emitter configuration,, and it is used as frequency receiver
What 3 factors that affect the output of a generator?
1:The strenght of the main magnetic Field. Determined by the strenght of the field magnets in a permanent magnet machine, or by the number of turns of wire on the field coils and the current through the coils in a wound field machine.
2: The number of armature conductors connected in series, which cut the main magnetic field. Determined by the number of turns on armature coils and weather the armature is lap or wave wound, which determines the number of armature conductors connected in series.
3: The speed at which the armature conductors cut the main magnetic field. The faster the armature cuts the magnetic Field, the higher will be the value of the voltage generated in the machine
For to keep the resonant frequancy constant L*C has to stay same. Lets say if you double L you have to divide C by 2 to keep the same resonant frequency. If only L increases Resonant frequency decrease, this is same for C.
What is the frequncy range of digital signal?
Telephone bandpass is 300Hz to 3000Hz. This is adequate for a recognizable and understandable voice, however the lack of high frequencies makes some people sound different on the phone.
Local calls often have a slightly wider bandpass, but long distance calls are sharply filtered to cutoff at exactly 3000Hz, to avoid spillover into adjacent channels during the process of frequency division multiplexing so that many voice connections may be sent on one line (e.g. twisted pair, microwave link, optical fiber) at the same time.
Why are homes powered by ac and not by dc current?
power station may also provide dc voltage with using of dc generator but it is not economical to transmit the dc voltage. Since the step up and step down of dc voltage is not possible directly using transformers, we'll have to transmit domestic supply voltage (DC, as your inquiry). But transmission of a DC voltage over lengthy lines would result in a much less voltage at receiver's end.
So, considering the efficiency, economy and easiness, AC is preferred to DC.
Voltage is a measure of electrical potential. I understood voltage best when my first semester Electronics professor told the class that voltage is to an electrical circuit as water pressure is to a plumbing "circuit".
List two differences between information signal and carrier signal.?
A: A carrier carry information by modulation either Amplitude or Frequency modulation. Therefore AM and FM RADIO M stand for modulation
How do you use Ac and DC multitester?
As applied to household AC conventions, there should be no voltage from N to Ground. Neutral is white, hot is black, ground is green. There should be voltage from black to N, Black to G, but not N to G.
Outlets are properly placed with the ground pin down, which puts N, to the left, and Hot to the right. Neutral is the wider one.
As applied to general electronics, the question needs a reference. There is AC, which takes two wires, and a Ground, which may be common to one lead of the AC, or separate, or exist at the center tap of a transformer, making each AC lead half the rms voltage of the lead to lead voltage.
With your multimeter set on voltage, stick one of the probes in the short slot and the other end in the ground opening. The meter should show 120volts. If not, stick one of the probes in the long slot and the other probe in the ground opening. If the meter shows 120 volts, then the polarity is wrong.
Another option would be to have the meter set on resistance. Stick one probe in the long slot and the other probe in the ground opening. There should be no resistance (the circuit will be closed). If the circuit shows open, relocate the probe from the long slot to the short slot. If the circuit shows closed, the the polarity is wrong. This assumes though, that the outlet actually has a ground wire hooked up to it.
