Synopsis About Electric Power and Electrical Energy Consumption

Electric power is an essential element of our daily life. Without electric power, humans would not have had the chance to invent and develop the technology that we have today. Electric power is used in various sectors, including industry, household, entertainment, and work. It is safe to say, without electrical energy, our life would be very difficult. Electric power is defined as the rate at which electrical energy is transferred per unit of time by a circuit. The usage of this electric power is measured in electrical energy consumption. A huge amount of electric power is generated and used simultaneously in our daily life. 

Sources of Electric Power and its Unit

Sources of Electric Power

There are many sources of electric power:

• Generators

• Batteries and dry cells

The generators also generate electric power from different sources:

• Solar energy

• Wind energy

• Geothermal energy

• Wave energy

• Biomass energy

The generated electric power is then transmitted to households and industries using electrical circuits.

Unit

Watt (W) is the SI metric unit of electric power. Joule per second (J/s) is equivalent to a watt. 

1 watt can be defined in two ways :

• The electric power is produced by a  1-ampere current flowing across a circuit with a Potential Difference of 1 volt. 

• When anyone does 1 Joule of work in 1 second.

Derivation of the formula for electric power

Power is work done per unit time. Therefore the formula of power (P) is work done (W) divided by unit time (t)-  P= W/t. 

It can also be written as P= E/t, where E stands for energy. 

The formula of electric power is derived from Ohm’s law. According to Ohm’s law, the formula of electric power is denoted as P= VI

We know that V= IR,

Or, P= I2R  [substituting the value of V=IR]

Or, P= V2/R [substituting the value of I=V/R]

Here,

• V stands for Potential Difference

• I stand for Current

• R stands for Resistance in a circuit

How are Electric Power and Electrical Energy Use related?

Electrical Energy Use (E)  can be defined as the Electric Power used for a certain time. Electric Power spent on any appliances or devices is termed Electrical Energy Consumption. Kilowatt-hours (kWh) is the commercial unit of Electrical Energy Use. 

1kWh is the Electrical Energy used when 1 kW of Electric Energy is spent in 1 hour. 

The formula for Electrical Energy Use is Power x Time. 

i.e, E= P x t

Or, E= VIt [ as we know, P=VI]

Or, E= I2Rt [ as we know, P=I2R]

Or, E= V2t/R [ as we know, P=V2/R]

Let us understand electric power use with mathematical examples,

Sum:

Dante uses his AC in summer for 2 hours. The power consumption of the AC is 3000 W per hour. Find out his electrical energy use.

Solution:

According to the problem,

P= 3000 W or 3 kW

t= 2 h

We know, E= Power x Time i,e, E= Pt 

Or, E= 3 x 2 kWh

Or, E= 6 kWh

Thus Dante used 6 kWh of electrical energy.

Sum

A sound system uses 60 kWh of electrical energy after running for 2 hours. If it draws 5 amperes of current, find the circuit’s voltage.

Solution

We know, E= 60 kWh

    t= 2 h

    I= 5 A

    V=?

According to the problem,

E= Vx I x t

Or, 60= V x 5 x 2

Or, V= 60/10

Or V= 6 volts.

Therefore the voltage used is 6 volts.

Applications of electrical energy and electric power

Some applications of electric energy and electric power are:

• Industries: Electrical energy is used in all kinds of industries. A separate electronics industry uses electric energy and manufactures electrical appliances. From smartphone manufacturing companies like Apple to electric car manufacturing companies like Tesla uses electrical energy.

• Household usage: Electrical energy is utilised in all households worldwide as a supply of power. Without electrical power, previous generations used to have fuel-burning lamps as their light source during nighttime. Electric energy provides power to all basic appliances in our household, such as fans, televisions, tube lights, microwave ovens, washing machines, etc.

• Cities: A city or town is also powered by electrical energy. Electricity flows through street lights and traffic lights. Many urban areas still lack an electricity system, and they have to use fuel lamps at night. This marks how important electrical energy is for development.

Conclusion

Electric power and the electrical energy consumption is an essential chapter in physics. Many sums and calculations come from these topics. Let us recall the principal points. Electric power has various sources, and the applications of electric power are known as electrical energy use. P= VI is the formula of electrical power. The formula for electrical energy consumption can be derived by multiplying time by electrical power consumed, E= Pt. There are innumerable uses of electrical energy. It controls every important aspect of our life. It is one of the reasons why science has developed so far.