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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
Why do we use 50ohm impedance for microwave circuits?
50 ohm is a great compromise between power handling and low loss,for air-dielectric coax..
What happens when emitter and collector of a transistor are short?
The transistor acts like a normal pn diode. in NPN transistor the both n i.e.,collector and emitter ane shorted then they become a n and other is p so pn diode is formed.
When the emitter and the collector of a transistor are short, the emitter current =the collector current.
What are the three factors that effect the electrical parameters of a op-amp?
Supply voltage , temperature , frequency are factors that effect the electrical parameters of opamp
What is the power dissipated a resistor with a current of 0.02 amps and a resistance of 1000 ohms?
P = I^2 x R]
P = 0.2^2 x 100
P = 4 W
What is phase between voltage and current in a pure inductive circuit?
The phase angle between voltage and current in a purely inductive circuit, under ideal circumstances where there is no resistance at all, is 90 degrees.
How can you increase the conductivity of a semi conductor?
The conductivity of a semi-conductor can be increased by raising the temperature of the semi-conductor .
Does a kettle have a printed circuit board?
If the kettle is a new one, then it should. If it is an older style kettle with no automatic shutoff, then it will probably not.
How can an ammeter be connected in a circuit and not effect the flow of current?
The ammeter does affect the flow of current in a circuit, however, the resistance of the ammeter is so small in comparison to the circuit that the effect is negligible. It is connected in series.
How do you convert sr filp flop to jk filp flop?
An sr flip-flop can be converted into a jk flip-flop by changing the forbidden state in the sr flip-flop so that the out put toggles instead when the s=r=1.
What is the application of mux?
mux is used to select a single input out of various inputs.eg. there are 4 inputs and u want to selext the first then u mail use the select lines as 00 for the first input
01 for second
10 for third
11 for fourth
Why transistorised inverters are prefered over thyristerised inverters?
The transistor allows you to turn it off when you want, while the thyristor, or SCR, will not turn off until the anode-cathode voltage drops below the cutoff voltage.
How does the cut in voltage effects the output of a diode clipper?
For answering this question we have to consider the constant voltage drop model of the diode which says that if voltage across diode is less then its cut in voltage than assume diode to be open circuit and if it is greater then assume diode to be short circuit.
Till the input voltage is less than the cut in voltage, diode is open circuit(thus no current through the circuit). Thus entire input voltage appears across the diode as output.
When input voltage is greater than or equal to cut in voltage, then short circuit the diode. Thus, there will be no voltage drop across the diode as output.
Thus cut in voltage decides when to consider the diode open circuit and when short circuit. It decides when the diode will have output when it will not.
Does the ohmmeter need to be parallel to the load when measuring resistance?
It does not matter, since the ohmmeter needs to be connected to the device in isolated mode. Series or parallel; they are both the same, in this case.
What is the self servo effect?
The self servo effect is used most commonly applications like drum brakes on vehicles. Most textbooks call this effect "self-energizing" and not "self servo". The rotation of the drum can drag either one or both of the shoes into the friction surface, causing the brakes to bite harder, which increases the force holding them together. This increases the stopping power without any additional effort being expended by the driver, but it does make it harder for the driver to modulate the brake's sensitivity. It also makes the brake more sensitive to brake fade, as a decrease in brake friction also reduces the amount of brake assist. Also, small changes in the coefficient of friction will cause large changes in the pedal force required for braking. This coefficient of friction change can be the result of temperature or more commonly, a wet surface (ie rain, puddles, etc.). The change from drum brakes to disc brakes occurred because of these reasons - disc brakes have better dissipation of heat, less wear, less susceptible to changes in coefficient of friction, and without self-energizing drivers can better gauge pressure placed on the brake pedal to prevent lockup. Not to mention drum brakes also are prone to "bell mouthing", and trap worn lining material within the assembly which can cause braking problems.
Why does an inductor offer high impedance to ac but very low impedance to dc?
Because an inductor resists a change in current. The equation of an inductor is ...
di/dt = V/L
... meaning that the rate of change of current is proportional to voltage and inversely proportional to inductance. Solve the differential equation in a sinusoidal forcing function and you get inductive reactance being ...
XL = 2 pi f L
Why Kirchhoffs current law and Kirchhoffs voltage law cannot apply on distributed circuits?
Actually, they do apply.
Kirchoff's Current Law states that the signed sum of the currents entering a node is zero. This applies whether the node has only two connections, such as in a series cicuit, or more than two connections, such as in a parallel circuit. Some people confuse this with the rule that current at every point in a series circuit is the same. That is just a special case of KCL, but the real rule has to do with the node, and not the circuit.
Kirchoff's Voltage Law states that the signed sum of the voltage drops going around a series circuit is zero. This applies for simple series circuits as well as for complex series/parallel circuits. Pick any loop in a circuit and walk around it - you will find that the signed sum of the voltage drops is zero, no matter what.
The 7400, and its variations, is a quad two input NAND gate.
Types of Negative feedback amplifier?
voltage amplifier feedback
current amplifier feedback
transconductance feedback
transresistance feedback
What is back charging of power transformer?
Do you mean "back-feeding"?
Normally a power transformer takes a primary voltage and steps it up or down (usually down) to a secondary voltage. However, transformers are symmetrical; you can just as easily feed the secondary and generate the primary voltage.
This is particularly a problem with utility power distribution systems in a storm, such as a hurricane situation...
In a protracted power outage, some people are tempted to run backup generators to supply their inhouse loads while the utility company is effecting repairs. An intelligent user, one that reads the directions, will isolate the generator from the service distribution system so that it is impossible to back feed the service source.
Some people might ignore the directions and attempt to back feed their entire home. If they don't isolate the incoming mains breaker, this can back feed the distribution transformer and energize the primary line on the street, raising it to high voltage, such as 7620 volts.
This actually happened during Hurricane Gloria in 1985, and a utility worker was killed. Yes, the worker was at fault for assuming that the line was dead, but the homeowner was also at fault for ignoring the directions that came with the generator.
Unless you have the proper equipment to synchronize, backfeed, and isolate your generator, DO NOT EVER DO THIS.
What feedback is used in amplifier?
there are four types of feedback connetion. the one used is that which amplifies your input (Positive feedback).
When soldering a replacement fitting in a refrigeration circuit it is important that?
You take into consideration the type of refrigerant used in the system.
