Electrical Engineering

The power factor of an RLC circuit under resonance is 1.

Explaination:-

Power factor of an RLC circiut is given by=R/|Z|

For a resonant circiut,|Z|=R (Because reactive components are zero in resonance)

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. .Power factor=R/R=1.

Three Phase transformers have three windings. If connected in Delta, it will have R Y B phase winding, voltage between RY, YB and BR. Phase voltage and line voltage are same.

If connected in Star, there will be a neutral as well with RYB. Line voltage and Phase voltage are different. Line voltage = 1.73 x Phase voltage.

I don’t know

A hum or other excessive noise can be caused by a misaligned or bent motor shaft. Likewise, this noise can be created if there is a minor fault in the transmission dividing the motor from the driven equipment, or even in the equipment itself. First feel the motor shaft for any obvious faults or bends. If nothing is noticeable, disconnect the motor shaft from the transmission and driven equipment, and then turn it on. If the noise is no longer present, then either the transmission or the driven equipment is at fault, not the motor.

In the name of Allah,the most Gracious,the most Merciful...

The Oscilloscope has several advantages over a voltmeter, for example if you want to determine a signal parameters [ voltage values (max,peak-to-peak,rms,average...etc),frequency,offset...etc ] using measurement tools:

1- You can use the Oscilloscope whatever the signal frequency is, but you can't use the Avometer unless the signal frequency is 50 to 60 Hz.

2- The Oscilloscope shows you the shape (form) of the signal, while the Avometer doesn't.

3- You can determine the maximum value of the signal (max voltage) and peak-to-peak voltage when you observe the signal on an Oscilloscope,hence you can calculate the rms (root mean square) value, i.e. the effective value , the average value and the offset of signal form the time axis (the horizontal axis).

While an Avometer can only give you the rms value.

superposition therorem states that in linear network containning more than one source of emf the resultant current in any branch is the algebraic sum of the current that would have been produced by each source of emf .taken sepertely with all other sources of emf replace by their internal resistance ........... that is called superposition theorem ..

do exist! Is there a real question about d.w.t's? On a double wound transformer, the primary winding is isolated from and secondary winding, but still use the same common core.

If its a filiment bulb, I'd say yes, if its other, then no. connecting it to a 240V grid would only make it go brigter (and probably a shorter service life)

A bourdon tube is a type of curved tube where the inside radius is smaller than the outside radius. As Force = Pressure x Area this means that when a pressure is applied internally to the tube the greater surface area on the outside causes the tube to straighten out. This is connected via a mechanical linkage to dial on the front of the gauge. Your typical industrial pressure gauge is the Bourdon Tube tyep.

In a wire, electrons are moving close to the speed of light, but they normally collide with the crystal lattice atoms and scatter (no fixed directions; can be deflected forward or backward or sideways). Adding an electric field to the wire (applying the ends of the wire to the terminals of a battery), we can nudge the electrons to have a net movement (an electron moving 10 steps forward but nine steps back has a net movement of one step forward) in one direction (the battery is supplying a DC current). When one electron leaves the wire (at the positive terminal of the battery), another electron has to enter the wire from the negative terminal to maintain electrical neutrality of the wire almost instantly. Hence the flow of information is still near the speed of light. Resistance is the measure of how quick is the net movement of electrons -- the slowly the net movement, the higher the resistance. A higher temperature makes the electrons (like going nowhere faster) and the lattice atoms (more vibration) more excited than a lower temperature. The extra atomic vibration makes the electron transition across a wire more difficult, although the electrons have sped up.

An analogy is filling a room with two exits, one to the right and the other to the left, with people standing. These people are ordered to give a push of any approaching person in a random direction (unpredictable). The room is situated on a level ground. You enter from the right by accident. You start bumping into the people in the room. Each person you approach gives you a push in a totally random direction. You may get out the exit to the right or move to the wall to the far end -- totally random. Note that no matter how fast you run, you feel you are not going anywhere in particular. Adding an electric field is like the room is being tilted so that the right-hand exit is higher than the left-hand exit. You have a net movement going to the left because of the aid of gravitational pull. A higher temperature means you run at a faster speed and the other people in the room are shaking randomly too. The resulting chaos slow your net movement to the left.

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a lamp in an elctrical circuit provides light and partly heat. a lamp in an elctrical circuit provides light and partly heat.

Because, the losses of IM is more due to the contribution of friction losses at shaft bearings and wind age losses in rotor air gap, this reduces the efficiency of the equipment, Since transforms is a static equipment zero mechanical loss so efficiency of the equipments in high .

You could try using nail polish remover, and if it doesn't work try a damp cloth not to damp and rub it gently on the area.

A: The reason is because as moving person you liable to generate kilo volts of static that when touching a circuit can and will destroy parts or worst unseen damage. The strap insure that no static can built because you are grounded to cause this kind of damage. In the industry it is mandatory if NASA has a project in the works. Get caught without it you are fired......

answer is actually voltage

It is simply the voltage of the system before the fault occurs.. Most probably this is the voltage of healthy system...

If there is no residual magnetism in the field poles then there would be no flux too induce the initial voltage for self exitation

To increase the current you either need to reduce the resistance of the load or increase the voltage. Typically a higher wattage light bulb will decrease resistance or you could put multiple batteries in series.

Power is inversely proportional to resistance.

Ohm's law: Current is voltage divided by resistance

Power law: Power is voltage times current, therefore power is voltage squared divided by resistance.

In electrical terms, a short circuit is an abnormally low resistance across the terminals of a power source, resulting in an abnormally high current-demand from the source, which typically exceeds its capabilities unless its output current is internally 'limited'.