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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
The reason that current leads voltage in a capacitor is rooted in the way a capacitor works. Picture the capacitor. It's basically two conductive plates separated by a short distance and having a dielectric (insulator) between them. Now, let's specify that our cap (capacitor) is completely discharged and we'll hook it up to a DC voltage source through a switch. Flip the switch on and current will begin to flow, but it is important to look at what happens in just the first instant of time. Electrons will begin to accumulate on the negative plate and their presence there will drive electrons off the positive plate. The capacitor is building up a charge. It is developing a voltage across (or between, if you prefer) the plates. But electrons have to begin to pile onto the plate to actually create the difference of potential (voltage) between the plates. The moving electrons (and that's current) that are piling on the plate are already beginning to flow before the voltage is developed between the plates, so current is said to lead voltage in a capacitor.
In a capacitor, the current flowing in it depends on the voltage difference across it. On AC, this makes it charge if the voltage is increasing above zero, and discharge if the voltage is reducing towards zero.
Because a capacitor has almost no internal resistance, and most loads that it is connected to have only very small resistances in series with the capacitor, the charging and discharging currents depend pretty much on the rate at which the voltage is changing. At the zero crossing point of the sine-wave, when the voltage is actually zero, the rate of change of voltage is very high (the sine-wave is at its steepest), so the current is also very high. If the voltage is positive-going, the current is positive, and if the voltage is negative-going, the current is negative.
At the peak of the voltage waveform, the rate of change of voltage is zero or very low (the sine-wave is just about flat, and not really changing its voltage) so the current is zero, too.
Since the maximum positive current occurs when the voltage is passing through zero, going positive, and the maximum negative current happens when the voltage is passing through zero, going negative, the current peaks happen 90 degrees before the voltage peaks, so the current is said to lead the voltage. This is the same as saying the voltage lags the current by 90 degrees.
What is normal telephone wire called?
I have always known it as 3 pair as it has 3 pairs of 3 colours. (blue, green and orange)
What is the total reactance of a series r-l-c circuit at resonance?
At resonance, the impedance of L and C completely cancel each other out, so you only have R left. If your circuit does not have any gain, then you should be able to determine the RMS current very easily by looking at the RMS voltage input divided by R.
What is the average cost of circuit board prototypes?
The average cost of these circuit board prototypes are they are a lots more than me and you got all together and it takes a special person that can afford these type of circuit board prototypes.
---- The output of JK flip flop :
J K Q(t+1)
---- 0 0 Q(t)
0 1 0
1 0 1
1 1 Q'(t)
----
the excitation table becomes:
Q(t) Q(t+1) J K
----
0 0 0 X
0 1 1 X
1 0 X 1
1 1 X 0 where X represents "don't care"
----
The out put of D flip Flop is:
Q(t+1) D
---- 0 0
1 1
---- Using MAP method, we find the function F
0 1
---- 0 X
1 1 X
----
F= J+K'
Therefore the JK flip flop becomes a D flip flop with an inverter paced just before the K entrance.
I would have shown you more if this site allow graphics!
What will happen if slip rings are removed from a DC motor?
It won't work. The slip rings work in conjunction with the brushes to connect a rotating part of the unit with the stationary part. We need to couple current into and out of the rotor, and without the slip rings for the brushes to ride on, we can't do that, and the motor won't work.
Usually, but some voltmeters are limited in the range of resistances they can measure.
AnswerNo, voltmeters measure voltage, notresistance.
What is the effect of bypass capacitor on frequency response?
Gain in a CE configuration of a BJT is collector resistance divided by emitter resistance, subject to the limit of hFe. The emitter bypass capacitor will have lower impedance at high frequency, so the gain will be higher at higher frequency, making this a high-pass amplifier.
What is bad about a series circuit?
In something like a lighting circuit, there are a couple of disadvantages to a series circuit. The first and most important is that all of the devices in the circuit must work. If you've ever dealt with Christmas tree lights you've seen the ones where one burned-out bulb kills the whole string. Second, the more bulbs in the circuit, the dimmer each one gets. But I think the worst one would be: you can't turn off any of the lights. If you turned one off, they'd all go out UNLESS you used a double-throw switch and a whole lot more wire so you could bypass any bulb you wanted to turn off. And when you did it, the lights that were still on would get brighter.
One of the disadvantage of a series circuit is in trouble shooting, you have to check ALL the loads of the circuit. Christmas light is the best example.
No advantage it is just a different What_are_the_disadvantages_in_using_a_series_circuitabove sample is lame because it will take as much time to find to open circuit in a parallel circuit.
In a series circuit, all components receive current in a row, and if the circuit through one is broken then none of the others can receive it.
In a series circuit any discontinuity of current flow will interrupt the rest of the circuit to operate.
*the more components the circuit has, the greater its resistance is.
*if just one component doesn't work, it opens the whole circuit.
i lay on the groudn and pretend im a carrot sometimes.
What can an egg be dropped into so it will not break?
try foam or something soft
or bubble rupp my name is Emily
What is the maximum length of a 1394a cable?
IEEE1394a runs at 400 to 3200 Megabits/second. aka Apple firewire.
How do you use a amp-volt-ohm?
I think you are refering to 'Ohm's Law' where Volts, Amps (I), Resistance (R) (measured in Ohms) have a specific relation to each other:
V = IR, Current x Resistance
I = V/R, Voltage/Resistance
R = V/I, Voltage/Current
Hope this helps, if so, please 'Recommend Contributor'
What will be the kva rating for 20a?
To answer this question the voltage of the circuit must be stated. That is what the v in kva stands for.
How do you identify the NPN transistor?
A transistor works by using a small amount of electricity to control a much larger supply of electricity, much like turning a valve to control a supply of water.
Transistors consist of three main parts - a base, a collector, and an emitter.
The base is the part for the larger electrical supply. The collector is the larger electrical supply, and the emitter emits that supply. By sending different levels of currents from the base, the size of the current can be regulated to the collector In this way, a very small amount of current may be used to control a large amount of current, like an amplifier.
ANSWER: A VOM can identify the transistor as NPN PNP just by checking the diodes inside the transistor. Example NPN positive lead to base should show low resistance to the other terminals
What is a thermistor typically used for?
A Thermistor is used in many devices that require a temperature reading. These can include fire alarms or vehicle engines. They range in sizes depending on the use. For example it can be small enough to fit onto a circuit board, or big enough to plug a hole in a hose.
Why is negative feedback used in high gain amplifier?
A: Well for one thing if it is positive feedback the amplifier will saturate to one one side of the power buss or the other. An operational amplifier open loop gain can be 90Db which a tremendous gain so some negative feedback is necessary to reduce the gain and make the amplifier behave in the linear region for amplification
Why a zener diode is better than a simple diode?
A typical diode functions only in one direction (forward-bias). When subjected to reverse-bias, the junction will eventually break down under high enough voltage. A zener diode works the same way, but breaks down at a very specific reverse-bias voltage. This is called its zener voltage. Because of this property, a zener diode can be used to regulate the voltage in a circuit. When inserted the opposite orientation as you typically expect a diode, it begins to conduct when the voltage across it reaches the zener voltage. Then the voltage stays at that level. See http://en.wikipedia.org/wiki/Zener_diode for more information.
What is resolution in instrumentation?
if input is slowly increased from some arbitary non zero input value it will again be found that out put doesnot change until certain increment is exceeded that increment is called resolution
How can the behavior of two magnets show the presence of a magnetic force?
suspend the magnets from strings in such a way that they only repel each other. (Between two glass plates maybe, so they can't rotate.) measure the angle of the strings.
Knowing the weight of each magnet, the acceleration of gravity, and the cosine of the angle between the strings this should give you enough to calculate the magnitude of the force between the magnets. (Providing you know vector addition of course.)
Baud rate is defined as the number of bits transmitted per sec.
How do you test the thermostat of your kwikot geyser?
Tools required: screw drivers, insulation tape - switch off your geaser, and plug out the power cable from the socket/power supply. Please also close the inlet water entry into your geaser. - remove the outer side of the geyser where the electrical connections are wired. This will need screwdrivers for most of the commercial geysers - Now you will see a big knob with temperature markings (usually 0 - 80 degree celsius) coming out of your geaser tank. - slowly track the electrical connections that is going into the thermostat and disconnect them (usually 2 of them) - Now pull the thermostat out - you will see a long rod coming out from the geaser. Now you are successful in pulling your thermostat out. - Now you want me to reverse-repeat the setps for plugging in the new thermostat in ? :-) - BTW...please note to set the temperature mark in the thermostat appropriately. Usually use the same as it was there in your older thermostat. - after plugging in the new thermostat, and you connect the electrical wiring, close the geyser (with whatever you removed) and open the inlet water entry. You need to plugin the power cable and switch it on again. Hope you find this useful, the new thermostat makes the geyser happy ! cheers, Harish
