What is inductance?

When alternating current passes through a conductor it will induce timely changing alternating magnetic field. According to lenz’s law this changing magnetic field induces an emf which is opposing it’s own cause (i.e. current through conductor). This opposition is called inductance. It is further segregated in to two parts self inductance and mutual inductance.

What is the relation between power factor and power consumption?

As we all know Total (Apparent) power = Real or Active power + Reactive power.

In a very simple language, power factor basically means, out of the total apparent power consumed by the load, how much useful or active or real power is present in it. In fact power factor is indicator of this above mentioned fact.

So, naturally power factor of unity (ideal case) indicates whole total power which is consumed by load is Active power or Real power, which means there is no reactive power consumed by load (case of Purely Resistive load).

As against this zero power factor indicates that no power will be transferred between the source and the load i.e whole power consumed by load will be just reactive power (just to get magnetized), no Active or real power is transferred which is actually used for doing useful work.

Consequences of low power factor and its effect on total power consumed by load:-

So, consider two loads, Load 1 and Load 2. Both have same power requirement for doing work (i.e Active power requirement). Now load one have low power factor, so as explained above out of total power which it draws from the source, Active power will have lesser share in it. load 2 has high power factor so the total power which it draws from source will contain more amount of Active power as compared to load 1 having lower power factor.

So, as the Active power requirement of both the loads is same, load 1 will have to draw more Apparent power (total power) as compared to load 2 which has high power factor, in order to have same amount of Active power as load 2.

Takeaway for you from this Answer:

A load with a low power factor draws more current than a load with a high power factor for the same amount of useful power transferred.

Thus, a load with low power factor will draw more apparent power as compared to a load with high power factor for the same amount of useful power transferred.

The higher current increase the energy lost in the distribution system, and require larger wires and other equipment.

Because of the above fact, Electrical utilities usually charges higher cost to industrial or commercial customers, where there is a low power factor.

We all feel electrical shocks. Which is really responsible for the shock, voltage or current?

The ultimate cause is the amount of electricity flow in the body, so it can be said to be current.

However, there are other factors, one of which is voltage, to consider:

1) Path of flow: If the internal organs are in the path of current flow, much smaller currents can cause a fatality.

Hence, if the shock is applied between one arm and the other arm, such as when holding Live wire in one hand and Neutral in the other, the current can pass through the heart, causing death. The same source of electricity may perhaps not be fatal if the points of the shock delivery are an arm and a leg, for example.

This is probably also the reason that execution by electrocution is done by placing the electrodes across the head. So that the current path is through the brain.

2) Resistance of the body: This is the resistance offered by the human body to electric flow. This can vary depending on moisture level. It can also vary with voltage as mentioned in the next point.

3) Voltage: Important to note that the resistance of the body changes according to voltage applied! Hence, it is not just a simple linear increase of current with voltage (in accordance with ohm's law).

The skin is an insulator, and contributes greatly to the high resistance of the body (order of Mega-ohms) for low voltages. However, at high voltages, dielectric breakdown of skin occurs which drastically reduces resistance of body by almost 1000 times!

This is what makes voltages above a certain level fatal, since it can cause current flow to increase drastically.

4) Duration of shock: In general, higher the duration of shock - greater the damage.

As an interesting example, consider static electricity. We can easily build up static potentials in excess of 10000 Volts, which is enough to break down air at short distances! However, we don't see any deaths caused by handshakes. :)

This is because, while the potential generated by static can be huge, the total amount of source charge available is really small. So the duration of the current flow is also too small to have any effect.

So to answer the question, while it is the flow of electrons (current) that causes us problems, there are other factors (including voltage) which can significantly affect how much of this electron flow occurs.

A Step Up transformer _____________. how ?

Ans: Step Up the level of Voltage & Step down the level of current

A Step up transformer only step up the level of voltage and step down the level of current.

Because the input power is same.

So according to P=VI→ I = P/V…. We can see that, when Voltage increases, current decreases.

So in Step up transformer, input power is same, therefore, when voltage increases, then current decreases.

If the frequency of 3-phase supply to the stator of 3-phase induction motor is increased, then synchronous speed is ________? Why ?

Ans:------ Increased

Explanation:   As we know that;   f = NSP/ 120

It is clear that f ∝ NS i.e., frequency (f) is directly proportional to the Synchronous speed (NS).

In more clear words, when frequency increases, Speed also increases.