# Class 10 Science Chapter 12 Electricity

In today’s world electricity is as important as breathing. Life will be 10 times harder if there is no electricity. But, uncontrollable electricity is no good to us. This is why it’s important to know the nature of electricity and how we can control it. In class 10 science chapter 12 electricity, we will be introduced to the basics of electricity.

What makes electricity? how does the current flow through the electric circuit? what factors control the electric current? all these questions and much more will be answered in this chapter. So, prepare yourself for an electrifying chapter.

## Class 10 Science Chapter 12 Electricity

We will start this chapter by first learning about the electric current and how a circuit is formed for the current to flow. We will look at some of the scientific formulas of current and the units in which it is measured. We will give a short summary of every topic that is there in class 10 science chapter 12 electricity.

# 12.1 — Electric current and circuit

To understand this topic properly, we must first know what is electric current? and what is a circuit?

What is electric current?

Just like the flowing water makes a water current in a river, the same way, when the electric charge flows through a conductor, it is called electric current.

What is an electric circuit?

A continuous and closed path of an electric current is called an electric circuit. It is expressed as the amount of charge flowing through a particular area in unit time, or the rate of flow of electric charges.

it is given by the formula I = Q/t (I → current, Q → net charge, t → time).
The SI unit of electric charge is coulomb (C).
The electric current is expressed in Ampere (A).

# 12.2 — Electric potential and potential difference

Class 10 science chapter 12 electricity teaches us that the electric current is produced by the flow of electrons, this means that if electrons do not flow, then there will be no current. So, we can say that movement of electrons is important to generate current. The electrons move only when there is a difference of electric pressure known as potential difference.

Electric potential difference: the electric potential difference between two points is defined as the work done to move a unit charge from one point to another.
It is given by the formula: V = W/Q (V → potential difference, W → work done, Q → charge).
The SI unit of electric potential difference is volt (V).

### Class 10 Science Chapter 12 Electricity

We have got hold of some basic about the electricity, like how the current is generated. We also got to know about different scientific terms. We will now strengthen our knowledge with the following topics.

# 12.3 — Circuit Diagram

There is not much theory to this section of class 10 science chapter 12 electricity. Building an electric circuit is practical work, but one must know how to draw a schematic diagram for different components of the circuit. In this section, you will see conventional symbols of some of the most used electrical components.

# 12.4 — Ohm’s law

Georg Simon Ohm was a German physicist who in 1827 discovered the relationship between the current and potential difference. According to him, the potential difference is directly proportional to the current (provided that the temperature of the wire through which the current is flowing remains the same). This relationship between the potential difference and current is called ohm’s law.

This relationship when expressed in the scientific formula gives:
V ∝ l
or, V/I = constant (R)
or, V = IR
here, R is a constant. It is called resistance.

Resistance: All conductors have the property to resist the flow of charges through them. The SI unit of resistance is ohm and is given by (Ω). From the above equations, we can say that current is inversely proportional to resistance. If we double the resistance, then the current will get halved. A rheostat is a device that is used to regulate the resistance in a circuit.

#### Class 10 Science Chapter 12 Electricity

Resistance is a very important aspect of electricity, without knowing resistance properly we won’t be able to control the flow of electricity. This is why it’s important to understand resistance. In the further topics of class 10 science chapter 12 electricity, we will learn various factors on which the resistance of a conductor depends.

# 12.5 — Factors on which the resistance of a conductor depends

The resistance (R) depends on:

• The length of conductor (l).  Resistance is directly proportional to the length of the conductor.
• Area of a cross-section of the conductor (A). Resistance is inversely proportional to the area of cross-section of the conductor.
• Nature of material that the conductor is made up of.

The above points give us the following equations:

R ∝ l/A
R = ρ * l/A

Here, ρ (rho) is a constant of proportionality known as the electrical resistivity. The SI unit of resistivity is Ωm.

# 12.6 — Resistance of a system of resistors

In class 10 science chapter 12 electricity, it is given that there are two methods of joining the resistors in a circuit i.e series and parallel.

12.6.1 — Resistors in series

When more than one resistance is joined end to end, then the resistors are said to be connected in series.

When several resistors are joined in series, the resistance of the combination equals the sum of their individual resistances and therefore is greater than any individual resistance. When one component fails in a series connection, then the circuit is broken and none of the components works.

12.6.2 — Resistors in series

When the combinations of resistors are connected together between two points, then they are said to be connected in parallel.

The reciprocal of the equivalent resistance of a group of resistances joined in parallel is equal to the sum of the reciprocals of the individual resistances. The circuit in parallel connection never breaks, even if most of the components fail.

##### Class 10 Science Chapter 12 Electricity

We have covered more than 60% of the topics that are given in class 10 science chapter 12 electricity. Now we will learn the heating effect of electric current and electric power. Make sure you understand all the topics covered in this chapter as it will help you greatly in higher classes.

# 12.7 — Heating effect of electric current

If an electric circuit is purely resistive, then the source of energy keeps on getting dissipated in the form of heat, and this is called the heating effect of electric current.

Joule’s law of heating: it implies that heat produced in the resistor is:

• directly proportional to the square of current i.e H ∝ I²
• directly proportional to resistance i.e H ∝ R
• directly proportional to time i.e H ∝ t.

All these points give the formula: H = I² R t

12.7.1 — Practical applications of heating effect of electric current

The heating effect of electric current is used in laundry iron, heater, oven, etc. It is also used to produce light in electric bulbs using tungsten. It is also used as a fuse in electric circuits.

# 12.8 — Electric power

The final topic of class 10 science chapter 12 electricity is electric power. The rate at which electric energy is dissipated or consumed in an electric circuit is known as electric power.  The formula for electric power is given by: p = VI. The SI unit of electric power is watt (W).