Electrical Engineering

Watt

You can't. You must supply the motor with it's required voltage. If it's a dual voltage motor, follow the wiring schematic on the motor nameplate to switch from low to high voltage.

Resistance is decreases then the voltage drop across it is decreases because of ohms law (V=IR),due to this power can also be decreases because of P=VI. so finally we can say that resistance decreases ,power also decreases.

Yes it depends on many variables such as what the wire is made of the size of the wire whether the wire is a multi strand wire.

What governs the amount of voltage a wire can carry is the insulation that is wrapped around the wire. Like wire with ratings of 300 volts, 600 volts and 1000 volts these are the highest allowable voltages that can be applied. A wire that is rated for 300 volts is good for 120 volts, 240 volts and 277 volts. At test research facilities, insulation is tested to destruction. The label that is given to the wire insulation as a result of the tests is the highest safest voltages that can be applied to that particular type.

Then the brightness of the light buld increases.

75 kV.A is the rated apparent power of the transformer which it can supply, continuously, to a load without overheating. When the transformer is not supplying a load, the primary current is (a) very small and, (b) lagging the supply voltage by practically 90 electrical degrees. Bear in mind that energy losses only occur for the component of current that is actually in phase with the supply voltage. So the energy consumed to the transformer is very small and is due to the resistance of the primary winding (copper loss) and a relatively small loss in the core (iron loss). Just how much energy this accounts for and, therefore, how much it costs to run the off-load transformer, is not possible to tell without knowing the full specification of the transformer.

yes

its a bit bigger Al in gauge for similar losses

so the bigger diameter Al also must be longer to get the required number of turns wrapped around the core (square cube law)

so may need a bit more steel in the core to accommodate the larger volume

Al costs less than copper

Steel cost less than Al

Cu doesnt oxidize as easily as Al

It is RFI generated from the ignition system. dI/dT very fast di/dt is rf

It is a variable resistance.

As you turn the volume control from low to high - or press buttons to do the same thing on miniature electronic items like mobile phones and MP3 players - the resistance of the volume control is reduced so that a higher current carrying audio waves can get through to the amplifier and so to the item's loudspeaker or headphones.

KVA is an acronym for killo volt - amperes. It is a measure of power (both real and reactive) defined as P = Vrms * Irms. If there is a power factor associated with this, it can be used to separate the real and reactive power:
P(real) = Vrms * Irms * pf
P(reactive) = Vrms * Irms * (1 - pf)

I'm not sure I understand the question. If you are asking if it's single or 3 phase, this will be marked on the name plate.

In a series circuit, the current does not change. It is simple the total voltage divided by the total impedence. However, in a parallel circuit the current splits. More current will go down the path with less impedence, and vice versa. For example, you have two parallel branches, 1 and 2, with resistances R1 and R2 respectively. Also, the total current flowing is I, while the current down each branch is I1 and I2.

I1= I(R2)/(R1+R2)

I2= I(R1)/(R1+R2)

Also note that I1 + I2 = I.

Yes.

You must understand that magnetic fields induce electric fields 90 degrees out of phase (or perpendicular) to them, and vice versa.

A charged particle will want to move one way or another when put within an electric / magnetic field, because the field will provide a push or pull on that particle in a specific direction.

The easiest physical way to view this is with two magnets - imagine a small stationary magnet. If you take another magnet and hold it close to the stationary magnet, the second magnet will be creating a magnetic field that will either push the stationary magnet away or draw it closer. The same thing can be done by creating an electromagnet (push current through a coil of wire near the stationary magnet).

If the overall load consists of:

'R' = resistance of each individual resistor

'S' = number of resistors in each series row

'P' = number of series rows connected in parallel,

then the effective overall DC resistance of the entire network is

[ R S / P ]

The residual magnetisation present in the current transformer coils may cause the errors during measurement of high currents. So that it is necessary to check that.

Ohm's Law states that 'the current flowing along a conductor is directly proportional to the potential difference across the ends of that conductor, providing all physical conditions, such as temperature, remain constant'.

Unfortunately, Ohm's Law applies to very few conductors and, so, hardly qualifies as a 'law' at all!

because the distance is propotional to the impedance of the line ,so the operation of the impedance relay comes into picture when the impedance seen by the relay is less than the pre-setting value.When a fault occurs ,the current increases to a high value and so the Impedence decreases and the relay actuates