# NCERT Solutions Class 12 Physics Chapter 3

## NCERT Solutions Class 12 Physics Chapter 3

Class 12 Physics includes various advanced Chapters related to different concepts and principles. Physics is considered to be one of the most interesting but tricky subjects. It is filled with numerous engaging concepts and problems. The concepts taught in Class 12 are the fundamentals of the subject. This subject is essential if a student is planning to pursue engineering, scientific research, and other similar fields.

Students are advised to focus and learn these concepts in-depth to develop their skills and build a strong foundation. Students can rely on the highly trusted Extramarks online platform for learning Physics and other subjects. Lakhs of students have already registered on the Extramarks website and got great scores in their Science subjects.

Our NCERT Solutions Class 12 Physics Chapter 3 is an essential study material for students preparing for school or competitive exams like JEE or NEET. This solution set will help students understand concepts in a better way to score well in their exams. With NCERT Solutions, students will get a detailed solution for all questions included in Chapter 3 Physics Class 12.

Extramarks team of expert faculties have curated the best study materials in our NCERT Solutions Class 12 Physics Chapter 3. Students can refer to our NCERT solutions to easily learn and understand the topics covered in the chapter Current and Electricity. Students may access the NCERT Solution by registering with Extramarks.

### Key Topics Covered In NCERT Solutions Class 12 Physics Chapter 3: Current and Electricity

Our NCERT Solutions Class 12 Physics Chapter 3 covers all topics of the Chapter Current and Electricity – current laws, relations, and concepts based on electricity.

Below we have given brief introductions to the key topics covered in this Chapter 3 of Class 12 Physics.

Introduction

Current is the flow of charged particles. It approaches the flow of charges that might be consistent withinside the Current Electricity. The electrons flow from negative to positive. It is because the electrons flow in the opposite direction. Also, the electrical current flows from higher electric potential to lower electric potential. In DC, the electric rate flows in a single direction. But, in AC, the direction of the electrical rate adjusts sporadically. DC is feasible from a cell or battery. AC is possible from the AC generator and mains.

Electric Current

Electric current is the motion of electrons via a conducting wire. Electric current refers to the range of charges that flow via the wire consistent with the second. It is the flow of electrons, while the current is the aggregate of the flow of charge consistent with unit time.

Electric Currents

It is the flow of electrons in a conductor. The motion of those charged particles creates a voltage or electric potential difference among points in a circuit. The potential difference between points is used for energy in electronic gadgets and appliances.

OHM’s Law

This law explains the relationship between voltage, current, and resistance, i.e. V=IR. The amount of steady current through many materials is directly proportional to the potential difference, or voltage, across the materials.

OHM’s Law is an important topic which will be used in many future theories and concepts of Physics. Our team has explained the law in more detail with real-life examples in our NCERT Solutions Class 12 Physics Chapter 3. Students can register on the Extramarks website and easily get access to our full NCERT Solutions study materials.

Drift of Electrons and Resistivity origin

The property of the material to oppose the electrical current is called resistivity. It is inversely proportional to the drift of electrons. The tendency of a material or device towards resistance is the resistivity of the device/circuit. Its SI unit is ohm-meter. The unit length across the cross-sectional area of the device is also resistivity. Therefore, the nature and temperature of the material also define resistivity (σ). σ= RA/L.

Mobility

Mobility is because the value of the drift velocity is consistent with the unit of electric field strength. Thus, the quicker the particle actions at a given electric field strength, the more mobility.

Limitations of OHM’s Law

As covered in our NCERT Solutions Class 12 Physics Chapter 3, below are a few of the limitations of Ohm’s law.

• OHM’s regulation isn’t relevant for unilateral electric elements like diodes and transistors as they permit the current to float through in a single direction only.
• The relation between V and I relies upon V’s (+ or -) sign. Suppose I is the current for a V. In that case, reversing the direction of V and maintaining its magnitude no longer produces a current of the identical magnitude as ‘I’ flows in the opposite direction.
• OHM’s law is only relevant in metal conductors. So it won’t work inside the case of non-metal conductors.

Resistivity of Various Materials

• A material with an excessive resistivity approach gives extreme resistance and could withstand the flow of electrons.
• A fabric with a low resistivity approach has low resistance, and as a consequence, the electrons flow easily through the material.

For Example, Copper and Aluminium have low resistivity.

• Good conductors have much less resistivity.

Temperature Dependence of Resistivity

Resistivity is indirectly proportional to the temperature. In different words, as you increase the temperature of substances, their resistivities will decrease. But this isn’t true for each material, i.e., all substances do not have an identical dependence on temperature.

Electrical Energy, Power

Electric energy is derived from the movement of electrically charged particles. When used loosely, electrical energy refers to the energy derived from electric potential energy.

Combination of Resistors: Series and Parallel

Combination of Resistors in Series:

The primary resistor’s output current flows into the second resistor’s input in a sequence circuit. Therefore, the current is identical in every resistor.

Combination of Resistors in Parallel:

In the case of a parallel configuration, every resistor has an identical potential drop across it, and the currents via every resistor can be different.

To know more about the combination of resistors, students may refer to our NCERT Solutions Class 12 Physics Chapter 3 study materials.

Cells, EMF, Internal Resistance

Cells:

An electrical cell or an “electrical power supply” converts stored chemical energy into electrical potential energy, allowing positive charges to flow through an external circuit.

EMF:

Electromotive force is the electrical potential produced through both electrochemical cells or by converting the magnetic field. EMF is the generally used acronym for electromotive force. A generator or a battery converts energy from one form to another.

Internal Resistance:

Internal resistance refers to the opposition to the flow of current offered by the cells and batteries, resulting in heat generation. Internal resistance is measured in Ohms. The relationship between internal resistance (r) and emf (e) of cells is given by:

e = I (r + R)

Cells in Series and Parallel

Cells in Series:

For a series connection, cells are joined end to end so that the same current flows via every cell. If the cells are linked in series, the battery’s emf is attached to the sum of the emf of the individual cells.

Cells in Parallel:

Cells are in parallel combination if the current divides amongst diverse cells. In a parallel combination, all positive and negative terminals are connected collectively.

The concept of Cells in series and parallel is important to understand the many circuits that would be coming in future chapters of Physics. Our academic team has given a few elaborative examples with step-by-step guidance on the actual working of cells in series and parallel in our NCERT Solutions Class 12 Physics Chapter 3.

Kirchhoff’s Rules

Kirchhoff’s First Rule:

Kirchhoff’s first rule (the junction rule) applies the conservation of charge to a junction. Current is the flow of charge, and the charge is conserved. Thus, whatever charge flows into the junction must flow out. Kirchhoff’s first rule requires that I1=I2+I3.

Kirchhoff’s Second Rule:

Kirchhoff’s second rule (the loop rule) applies to energy conservation. The loop rule states in terms of potential V rather than potential energy, but the two are related since PEelec=qV.

Note:

Recall that emf is the potential difference when no current is flowing.

Wheatstone Bridge

It is a circuit used to determine an unknown electric resistance by balancing the legs of a bridge circuit, one portion of which incorporates the unknown component. The Wheatstone bridge works on the null deflection principle. It means that the ratio of their resistances is equal, and no current flows through the circuit.

Meter Bridge

A meter bridge also referred to as a slide wire bridge, is a tool that works on the principle of a Wheatstone bridge. A meter bridge is used to locate a conductor’s unknown resistance as that of a Wheatstone bridge.

Potentiometer

A three-terminal resistor with a sliding or rotating contact forms an adjustable voltage divider.

### NCERT Solutions Class 12 Physics Chapter 3 – Exercise & Answer Solutions

Extramarks is considered to be one of the best academic platforms for students. Our Class 12 Physics Chapter 3 NCERT Solutions will help students prepare well for various competitive examinations like JEE or NEET and even school-level examinations and consequently score good marks. The subject matter experts at Extramarks have curated these Solutions and explained them in simple and easy-to-understand language.

Click on the links below to get access to exercise and answer solutions covered in our NCERT Solutions Class 12 Physics Chapter 3:

• Chapter 3: Exercise 3.1 Solutions
• Chapter 3: Exercise 3.2 Solutions
• Chapter 3: Exercise 3.3 Solutions
• Chapter 3: Exercise 3.4 Solutions
• Chapter 3: Exercise 3.5 Solutions
• Chapter 3: Exercise 3.6 Solutions
• Chapter 3: Exercise 3.7 Solutions
• Chapter 3: Exercise 3.8 Solutions
• Chapter 3: Exercise 3.9 Solutions
• Chapter 3: Exercise 3.10 Solutions
• Chapter 3: Exercise 3.11 Solutions
• Chapter 3: Exercise 3.12 Solutions
• Chapter 3: Exercise 3.13 Solutions
• Chapter 3: Exercise 3.14 Solutions
• Chapter 3: Exercise 3.15 Solutions
• Chapter 3: Exercise 3.16 Solutions

Students can also explore all types of educational content on the Extramarks website for Class 1 to Class 12. Click on the respective links below to know more.

• NCERT Solutions Class 1
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• NCERT Solutions Class 12

### NCERT Exemplar for Class 12 Physics

NCERT Exemplar book is a collection of a variety of questions for students to practice and become stronger with the subject. The Exemplar includes a lot of questions from the chapter, including short questions, long format questions, MCQs, etc.

By solving the questions from Exemplar, students will be able to revise the chapter and also understand their weak sections. So they can revise these sections to gain more confidence in their final exams.

After referring to the NCERT Solutions Class 12 Physics Chapter 3 and NCERT Exemplar, the students will have a comprehensive understanding of the Current and Electricity chapter. Our study notes also contain solutions for all the questions covered in NCERT Textbook and NCERT Exemplar books.

### Key Features of NCERT Solutions Class 12 Physics Chapter 3

Students may not be able to grasp the subject completely by studying from NCERT textbooks. Hence, Extramarks has created a set of NCERT Solutions Class 12 Physics Chapter 3 Notes to aid students in understanding the topic and preparing for exams.

Some of the most important aspects of learning from Extramarks’ NCERT Solutions Class 12 Physics Chapter 3 Notes include:

• Extramarks’ CBSE Revision Notes, as well as the NCERT Solutions Class 12 Physics Chapter 3 Notes, are developed by subject specialists, particularly for students seeking extra help and scores for their Examinations.
• Every topic in the Chapter is thoroughly explained in these Notes. All of the Notes are written in plain, straightforward language.