Science is an important subject concerning the CBSE class 10th exam. Preparing for the 10th exam involves hard work and dedication to study every subject covering all the chapters mentioned in the syllabus.
CBSE 10th science consists of 16 chapters in all. Out of which four chapters are from Physics. Physics being an interesting subject can help you score well in the CBSE 10th Science exam. Due to the numerical questions asked in this section, students can score full marks if they have their concepts clear.
Chapter 12 from the CBSE 10th Science deals with the concept of electricity. Learning the concepts from this chapter becomes easier as students can relate the concepts to the use of electricity in their daily life. Having clear concepts from this chapter will help the students secure marks that would fetch them a good score in the CBSE 10th exam. Students are also expected to study this chapter from the NCERT solutions for CBSE class 10th.
Electricity has become an integral part of our lives in this modern world. We use electricity for almost everything. Thus, we must study the concepts related to electricity. Read this article to get a clear idea of the concepts discussed in the chapter Electricity from the CBSE class 10th Science. Following mentioned are a few basic concepts from this chapter:
Basics of electricity
- Electric current (I): The rate of flow of electric charge through a conductor is called electric current. A charge is a fundamental positive or negative particle of an atom.
- Electric circuit: Electric current flows when there is a continuous path present. This continuous path which allows the electric current to flow through it is an electric circuit. A switch is used to make or break the path of an electric circuit.
- Electric potential is defined as the amount of work done to move a unit charge from a reference point to a specific point against an electric field.
- Potential difference (V): Potential difference is the work done to move a unit charge from one point to another. It is denoted by V.
Current always flows from a point at the higher potential to a point at the lower potential.
- Resistance(R): It is the property of a conductor to resist the flow of current through it.
The law states that the current flowing through an ideal conductor is directly proportional to the potential difference across the ends, provided that the temperature remains constant.
V = IR
To get an in-depth knowledge of the chapter, go through the CBSE 10 Physics concepts.
Factors affecting the resistance of a conductor
The resistance of a conductor depends on several factors. The resistance either increases or decreases with a change in these factors.
To be precise, the resistance of any conductor depends on :
- The length of the conductor
- The cross-sectional area of the conductor
- Nature of the material used in the conductor
Observations show that the resistance of a metallic conductor is directly proportional to its length and inversely proportional to the cross-sectional area of the conductor. The material used in the conductor determines its resistance by a property of the material called the resistivity of that material with an SI unit as Ohm metre.
Metals and alloys, which are good conductors of electricity, have a low resistivity value, whereas insulators like rubber and wood have a high resistivity value.
Heating effect of electric current
It is common to observe that electric appliances get heated up when used for a long time. The heating up of electrical appliances is due to the source of energy. The energy from the source is being used up to perform the functions of the appliances. However, energy also gets expanded to increase the temperature due to the presence of resistors. This heating up of the appliances is called the heating effect of electric current.
When the circuit is purely resistive, the energy from the source is continuously used up to increase the temperature. The heating effect in such circuits is used in appliances like electric heaters, electric iron, electric geysers etc.
Consider a current I flowing through a resistor of resistance R with a potential difference V and Q is the charge that flows for time t then the power input to the source is
P = VQ/t=VI
The energy supplied to the circuit is P×t which is the same as VIt. This energy is nothing but the heat produced. Thus, heat H is shown as
H = VIt
Applying Ohm’s law here,
H = I2Rt
The above equation shows that heat produced in a resistor is directly proportional to the square of current passing through the resistance, the resistance of the given current and the time for which the charges flow through the circuit.
Similar to mechanical power, electric power is defined as the rate of doing work. Electric power (P) is thus the rate at which an electric circuit per unit time dissipates the electrical energy.
Power (P) = VI
V = IR
Therefore, P = I2R
Also, I = V/R
Therefore, P = V2/ R
Usually, electric generators are used to produce electric power. However, devices such as electric batteries can be used to supply electric power.
Electric power grids are installed to supply electricity for domestic and industrial use.
Watt is the SI unit of electric power. For instance, if one joule of energy is used for one second, electric power equals 1 watt.
While watt is a very small unit, in day to day life, we use a larger unit which is 1 kilowatt. Electric energy is a product of electric power and time with a unit as watt-hour(W h). When 1 watt of power is used for 1 hour, 1 Watt-hour of energy is consumed.
The electric energy used commercially is usually described in kilowatt-hour(kW h), commonly known as units.
1 kW h = 1000 watt * 3600 seconds
= 3.6 * 106 watt seconds
= 3.6 * 106 joule
Chapter 12 from the CBSE class 10th Science is a detailed description of some of the important concepts related to electricity. It discusses various facts and terminologies of electricity.
Students are expected to solve numerical questions based on this topic to score well in their exams. The numerous questions solved in the NCERT solutions for class 10 science from this chapter will help students practice and prepare the topic well.
To thoroughly practise the chapter, solve the sample papers and previous years’ question papers for CBSE 10th. It will help students to be great at scoring their exams.