Class 10 Science

# Electricity

Electricity is a type of energy that is the result of movement of electrons between two points when potential difference is present between two points.

We cannot imagine modern life without electricity. You can easily make a list of hundreds of useful items which become useless in absence of electricity.

• Electricity is easy to produce. Electricity can be produced by using various fuels such as coal and petroleum. Electricity can be produced by harnessing kinetic energy of water, solar energy and wind energy.
• Electricity is easy to transport. Electricity can be easily transported over long distances by means of wires.
• Electricity is easy to transform. Electrical energy can be easily transformed into other forms of energy such as light, heat, kinetic energy, mechanical energy, etc.
• Electric current
• Electric circuit
• Mathematical expression of electric current

These notes are based on the chapter Electricity class 10 science of NCERT book and CBSE syllabus.

## Electric Current

The flow of electric charge is known as electric current. Electric current is carried by moving electrons through a conductor.

Fig: Conventional Flow of Electric Charge

By convention, electric current flows in opposite direction to the movement of electrons. As shown in this figure, electron flows from negative terminal to positive terminal. As a result, electric current flows from positive terminal to negative terminal. Blue line shows the flow of electrons. Red line shows the flow of electric charge.

## Electric Circuit

Electric circuit is a continuous and closed path of electric current. If the circuit is complete, i.e. not broken, it is called a closed circuit. If the circuit is not complete, i.e. broken, it is called open circuit. When you switch on an electrical appliance then electric circuit becomes closed circuit. When you switch off an appliance then electric circuit becomes open circuit.

### Expression of Electric Current

Electric current is denoted by letter I. Electric current is expressed by the rate of flow of electric charges. Rate of flow means the amount of charge flowing through a particular area in unit time.

If a net electric charge (Q) flows through a cross section of conductor in time t, then:

text(Electric Current) (I)=(text(Net charge) (Q))/(text(Time) (t))

Or, I=Q/t

Where,I is electric current,Q is net charge and t is time in second.

#### SI unit of Electric Charge and Current:

SI unit of electric charge is coulomb (C).

One coulomb is nearly equal to 6 xx 10^18 electrons. SI unit of electric current is ampere (A). Ampere is the flow of electric charges through a surface at the rate of one coulomb per second. This means if 1 coulomb of electric charge flows through a cross section for 1 second, it would be equal to 1 ampere.

Therefore; 1 A = (1 C)/(1 s)

Small quantity of Electric Current: Small quantity of electric current is expressed in milliampere and microampere. Milliampere is written as mA and microampere as μA

1mA (milliampere)= 10^(-3) A

1μA(microampere)=10^-6 A

Ammeter: An apparatus to measure electric current in a circuit.

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