Some basics from Electrical Engineering

The basics of electricity starts at Farday’s Law of Induction
A magnet creates flux and if this flux is interrupted, an emf is produced (to put it simple) in a closed circuit

Voltage

This emf can be otherwise called voltage
Voltage is the potential difference between two points
A potential difference is required for the flow of current
For example : water flows from higher spot to lower spot
The difference in height makes the flow of water
Similarly, the difference in potential makes electrons to flow
So, when we mention, voltage as 230 Volts, this means, the potential difference between one point of the electric connection ie, phase and the other , ie neutral is 230 Volts
Like higher the height difference, greater the flow of water, higher the potential difference, greater the current flow
Also, water flow depends on the resistance offered by the medium through which it flows.
In case of electricity, the flow of electrons depends of the resistance of the conductors through which it flows
In short, Potential difference or voltage can be compared to the height difference and the water flow can be compared to flow of electricity
Flow of electricity is called current and is measured in Amperes

The flow of electricity depends on potential difference and resistance
ie, Rate of flow of current is directly proportional to the potential difference and indirectly proportional to the resistance
This is Ohm’s law

When electricity flows through a human body, it is called electric shock
Thon potential difference at which the body is in contact and the resistance of the body
100 milli ampere is the maximum safe current that can pass though a human body
e quantity of current flows though the body depends
A potential difference of 230 Volts may cause a current flow more than this safe limit that may lead to death
Suppose, a human body comes into contact with the phase of 230V supply.
If he/she is bare footed, and the resistance of the body is 1 Kilo Ohms, the current flow will be 230V/1000 Ohms = 0.230 Ampere or 230 Milli Ampere
A foot ware or an insulated material underneath the feet may prevent electric shocks
If the human body is exposed to higher potentials, dangers are more and it may cause instant death

Power is the combined effort of the potential difference and current
It is the product of voltage and current
Power is expressed in watts •Watts = Voltage x current x power factor
Power factor is a constant that denotes the actual power that is used by an equipment to work
Every equipment has reactance along with resistance.
Electric power supply system has to provide power to this reactance additionally
This power is called reactive power
The ratio between the total power consumed by the equipment and the power supplied by the power supply system is called power factor
ie, pf = watts / volts x apmpere ( W/VA)
All electrical equipment have power factor depending on the inductance and capacitance of the equipment.
An induction motor has 0.8 pf and an electric lamp has 1.0 pf (approx)
Power is expressed in watts. •Watts = current x volts x power factor = I x V x pf
A 3 Phase, 415 Volts, 50KW induction motor takes 87 Ampere current with a pf of 0.8

Energy is the total power consumed in a particular time
It is expressed in Watt-Hour
If a 100 watts lamp works for 2 Hours, the energy consumed is 100 x 2 = 200 watt-Hour
Energy is measured by the Power Distributers in “Units”
1 Unit = 1 Kilo Watt Hour
This means, if a power of 1000 Watts (1 KW) is consumed in 1 Hour, 1 Kilo watt Hour energy or 1 unit of electricity is consumed
1 KWH = 1 Kilo watts x 1 Hour ( 1000watts x 60 minutes)
Similarly, for a 100 watts lamp to consume 1 unit it has to work for : 1 KWHr = 100 watts x t hours or t = 1 KWHr / 100 Watts = 1000 watt hour / 100 watts = 10 Hours

Batteries are another source of electrical energy
Chemical Energy is converted into Electrical energy here
Battery’s power is expressed in A-H ie, Ampere-Hour
A Battery with 1 ampere hour capacity can supply a current of 1 ampere for 1 hour or 0.5 ampere for 2 Hours and so on
While selecting batteries, it is important to choose them in accordance with the voltage requirements and the ampere-hour requirements

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