Class 10 Electricity Notes

One of the most important chapters of Class 10 Physics, Electricity explores the basics of electric power and electric current and familiarises learners with the concepts of Ohm’s Law, Joule’s Law of Heating, and resistance, amongst others. It aims to teach the importance of electricity in modern society and its different uses in different industries. This chapter not only emphasizes what constitutes electricity but also covers how to control it and use it better. Looking for physics notes for the Class 10 Science chapter on Electricity? Here are a complete summary and Class 10 Electricity notes to help you understand the key points and concepts covered in this chapter!

Electric Current and Circuit

Electricity is a flow of electrical charge that contains the transfer of electrons from one atom to another. This electric charge can be either positive or negative and creates an electric field. When these electrons flow in an electrical circuit continuously, it creates an electric current. While going through our Class 10 Electricity notes, you must remember that electric current is a net flow of electric charge that passes through a particular region and is carried by the charged particles only. In an electrical circuit, the electric current’s direction is always opposite to that of the direction of the flow of negatively charged electrons. A circuit has a pivotal role in the same as it forms the path that lets the electricity flow from one point to another. An electric circuit also forms a loop to enable the smooth flow of the current.

E.g., A lamp powered by a cell and connected through a cable with an on/off switch. When the switch is on, it creates a circuit and maintains the flow of charge to keep the lamp on. If the switch is turned off, it breaks the circuit, the flow of charge stops switching off the lamp.

Electric Current (I) = Net Charge (Q)/Time (T)
or
I = Q/T

Further, as per the Class 10 chapter on Electricity, the SI unit of electric charge is Coulomb (C) and it is considered to be equivalent to the charge contained in nearly 6 × 1018 electrons. We measure electric current by a unit called Ampere (A) which is named after the famous French Scientist, Andre-Marie Ampere.

A = 1 C/ 1 s, i.e. One Ampere is a total of the flow of one Coulomb of charge per second.

Micrampere (1 μA = 10^-6 A) or Milliampere (1 mA = 10^-3 A) is referred to as small quantities of current. Want to know how to measure electric current in a circuit? It is calculated by an instrument called an ammeter. Here is a diagram of an electric circuit which is constituted of an electric bulb, a cell, a plug key as well as an ammeter. See how the electric current in the circuit goes from the positive terminal to the negative terminal of the cell.

Electric Power and AC

Current Joule’s Law’s Heating Effect:

• Heat (H) ∝  square of the current (I).
• H ∝ Resistance of the given circuit.
• H ∝  Time (t) for which current flows through the conductor.

When a potential difference is generated, electrons travel, resulting in current flow.

Conductors and Insulators

Conductors are substances that provide comparatively less resistance to the passage of electricity, whereas insulators provide more resistance.

Electric Potential and Potential Difference

The next section you must study in Class 10 Electricity notes is what is electric potential and potential difference. An electric charge does not flow on its own and requires a medium for movement. For maintaining the flow of charge, the electrons need the difference in electric pressure that is called a potential difference. We can refer to an electric potential difference as the total work completed to move a unit charge from one point to another in a current-carrying electric circuit. Here is the formula to find the potential difference between the two points:

V = W/Q
Here, V = Potential Difference
W = Work Done
Q = Charge
The potential difference is measured by a voltmeter.

Circuit Diagram

To draw a circuit diagram, it is essential to know its components and their respective diagrams. This is one of the important questions asked in the Class 10 Science exam thus you must remember the following components of the Circuit Diagram and their respective symbols:

Ohm’s Law

In 1827, George Simon Ohm, a German Scientist, explored the relationship between the current flowing through an electric wire and the potential difference. He realized that the potential difference caused is proportional to the current flowing through an electric circuit given the temperature is the same. Thus, Ohm’s Law states that the current flowing through the ohmic conductor between its two endpoints is proportional to the applied potential difference.

Ohm’s Law

V = IR 
Here, R = resistance
V = potential difference
I = current

Factors on Which the Resistance of a Conductor Depends

The Class 10 Chapter on Electricity notes that resistance can be simply defined as the characteristic of a conductor that results in resisting the flow of electric current passing through a conductor. A resistor is utilized to resist the flow of electric current in a circuit and practically, they are simply applied for increasing or decreasing the electric current. While going through our Class 10 Electricity notes, you must know that the positive components of a conductor lead to a hindrance to the electron flow due to the attraction between them. Then, this hindrance is considered as the main cause of resistance in the electricity flow.

The factors on which the resistance of a conductor depends are as follows:

1. Nature of the material
The materials which lead to the least resistance are referred to as good conductors such as silver which is often called the best conductor of electricity. On the other hand, when materials create hindrance, they are called bad conductors or insulators like plastic.

2. Length of the conductor:
Since resistance (R) is always considered directly proportional to the conductor’s length, the increased resistance automatically results in the increased length of the conductor. This is why you must have noticed that long electric wires have more resistance to electricity.

Resistance (R) ∝ length of conductor (l)
or,
R ∝ l

3. Area of the cross-section:
When it comes to the area of cross-section, the resistance is always inversely proportional to it.

Resistance (R) ∝ 1/Area of a cross-section of conductor
R ∝ lA
R = ρ lA
Here,  ρ (rho) is the proportionality constant and is also referred to as the electric resistivity of the conductor’s material

The SI unit of resistivity (ρ) is Ωm or Ohm Meter.

Resistance of a System of Resistors

The next concept covered in our Class 10 Electricity notes is the resistance of a system of resistors. This section explores how Ohm’s law can be applied on the combination of resistors. Here are the two main combinations of resistors:

1. Resistors in Series

Resistors in Series are when resistors are joined together from one end to another thus forming a series. Here, the total resistance can be calculated by the sum of the resistance of all the resistors in the series.

The potential difference between A and B here is V and the potential difference between all the resistors, i.e. R₁, R₂ and R₃ = V₁, V₂ and V₃. I is the current flowing through the series. Thus,

V = IR_s

2. Resistors in Parallel

In this combination, the resistors are connected in a parallel manner. In Resistors in Parellel combination, the total current I, is equal to the sum of the separate currents and let’s suppose that R_p equivalent resistance of the parallel combination of resistors.

I = V/R_p
Here, V/R_p = V/R₁ + V/R₂ + V/R₃
or
1/R_p = 1/R₁ + 1/R₂ + 1/R₃ 

EMF and Terminal Voltage

• When there is no current flowing through the circuit, the potential difference between the two terminals of a cell is called EMF.
• When current is flowing through a circuit, the potential difference between the two terminals of a cell is called terminal voltage. ​​

Heating Effect of Electric Current

The heating effect of the electric current explains that during the flow of electrical current, the energy source is required to keep expanding to maintain the flow of current. Some part of this energy is consumed in useful work while some part is expended in the form of heat and raises the temperature. When the source energy gets dissipated continually in the form of heat, it creates the heating effect of electric current.E.g., An electric fan becomes warm when used for a longer duration continuously. Studying this section in our Class 10 electricity notes, you must also explore how this phenomenon is explained by Joule in terms of Joule’s law of heating. This law indicated that in terms of a given resistance, the heat produced in a resistor is always directly proportional to the current’s square as well as it is directly proportional to the given current’s resistance.

Applications of Heating Effect on Electric Current

During the electric current, heat gets dissipated and converts the useful electrical energy into heat. This heat is dangerous for electrical circuits if it goes beyond the acceptable limit, as it might damage the important component by raising the temperature. However, the heating effect of electric current can be useful when utilised properly. Appliances like an electric toaster, oven, kettle, heater, iron, etc. use the Joule’s law of heating to make proper use of heat dissipated during the electric current. An electrical bulb uses the electrical heat to produce the light. A bulb’s filament is made of tungsten with a high melting point of 3380°C and cannot be quickly melted. So, when the heat is generated during the electrical current, it absorbs the heat, gets hot and emits the light. 

Electrical circuits also use Joule’s law of heating. Going through the Class 10 Electricity notes, you must remember that an electrical circuit has a fuse component that protects the circuit in case of any rapid increase in electric current. A fuse is made up of a low melting point alloys or metals like copper, iron, lead, etc. When the electrical current increases than the specified value, the temperature increases and melts the fuse wire. Thus, it breaks the circuit and saves the appliance from any damage.

Electric Power

The rate at which the electric energy is dissipated in an electric current is called electric power. The SI unit of electrical power is the watt (W), and the unit of electric energy is watt-hour (W h). Because the unit watt is relatively small in the calculation, it is often replaced by the kilowatt. One kilowatt equals 1000 watts.

Power P = VI
Or P = I2R = V2/R

Since electrical energy is a product of power and time, the commercial unit of electric energy when 1 watt of power is used for 1 hour is defined as kilowatt per hour (kW h) known as a unit.

Class 10 Electricity Important Questions & Solutions

Now that you are familiarised with the major concepts of this chapter through our Class 10 Electricity notes, here are some important questions and solved numerical for you:

• State the major factors that can affect the resistance of a conductor.
• Explain how the voltmeter measures the potential difference between two points in an electric circuit.
• Name the SI unit of electric current.
• What do you understand by conductors?
• What is Joule’s Law of Heating?
• What is Ohm’s Law?

Here are some solved examples on the aforementioned topics covered in Class 10 electricity:

Q: What will be the power of the bulb if connected to a 220V generator with a current flow of 0.50A? 
A: => P = VI
   => 220V X 0.50A
   => 110 J/s
  => 110 W

Q: An electric bulb draws an electrical current of 0.5A for 10 minutes. What will be the amount of electric charge in the circuit?
A: => Q = I (Electric current) x t (Time)
   => 0.50A X 600s (Convert minutes into seconds)
   => 300C

Thus, we hope that this blog on Class 10 Electricity notes clarified all your doubts on this chapter and provided you with a comprehensive summary! Confused about selecting the right stream after 10th? Reach out to our Leverage Edu counselors and we will guide you in finding the best stream of study which aligns with your career aspirations and interests!