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NCERT Exemplar Class 12 Physics Chapter 1 Solutions: Electric Charges and Fields

NCERT Exemplar Solutions for Class 12 Physics Chapter 1 provides you with clear concepts of electric charges and its fields. The problems in this chapter of NCERT Exemplar Class 12 Physics are presented in 5 sets of exercise which brush up your knowledge on calculating the force between two particles that are placed at a distance from each other, explanation of why charge appears when there is a friction between two materials, conductors, insulators, Coulomb’s law, Gauss’s law and applications of these laws, electrostatic fields, electric flux, and dipole.

This chapter has a total of 31 NCERT Exemplar problems divided into different sections such as objective type (MCQ) where MCQ1 has only one right answer while MCQ2 has one or more than one correct answer, very short answers, short answers, and long answers.

Instasolv provides solutions to these NCERT Exemplar problems for class 12 physics chapter 1 in a way that will clear up many of your doubts. Even the complex questions are broken down into multiple steps to give you better insight into how we derive the solutions. This is an important chapter and with the aid of various tips and tricks from Instasolv, you should be able to fare well in your CBSE exams as well as other competitive exams.

Important Topics for NCERT Exemplar Class 12 Physics Solutions Chapter 1 – Electric Charges and Fields

An Electric Charge

  • Every matter has a physical property by virtue of which it either attracts or repels another matter; this is its electric charge. 
  • An electric charge could be either positive or negative. Charges of the same type repel each other and charges which are opposite, attract each other.

Properties of an Electric Charge

    • Additivity – This says that in a system if you sum up all the charges present anywhere in it, then algebraically summing them all will give the total charge of a system.

If ch1, ch2, ch3, … chn  are point charges then the total charge is:

chtot = ch1 + ch2 + ch3 +…..+ chn

    • Conservation – In an isolated system, the total charge is constant and never changes. The total positive charge minus the negative charge is always the same in the universe.
    • Quantization – Quantization of charge for any object denotes how many times the charge of a single electron is, in that object. 

          Charge = n * e

Here n is an integer

e is the charge (proton is + and electron -) = 1.602192 X 10-19

      • Electric field – Any charge produces a field around it which is its electric field. This force is exerted on objects which come near the charged matter.
        • Source charge – This is the particle which is generating the electric field
        • Test Charge – This is the object experiencing the force of the source object.
  • Coulomb’s Law – When 2 point charges are brought close to each other then they exert a force on each other which is:
      • Inversely proportional to d², where d is the distance between the point charges.
      • Directly proportional to the magnitude of the charges multiplies together.
      • The direction of force is on the lines which join the 2 points.

F (force) = n ch1 ch2∣ /

Here n is the coulomb’s constant = 1/4π ε0

ε0 = permittivity of space = 8.854 x 10-12 C2 N-1 m-2

This law has been applied in many spheres like Xerox machines, laser printers, etc.

    • Electric Dipole – A pair of charges which are equal and opposite, say +Ch1 and –Ch1 and there is a distance 2d between them, then they form a dipole.
    • Gauss Law – The total electric flux within a closed surface is equal to the total charges inside divided by its permittivity. The permittivity of a space is the capability of a vacuum to allow electric charges. It is a constant represented by ε0.

ϕ ε0

Here Q = total charge

                                ε0 = 8.854 x 10-12 C2 N-1 m-2

ϕ = total flux

This law is used to solve many complicated electrostatic problems.

Discussion of Exercises of NCERT Exemplar Class 12 Physics Solutions Chapter 1 – Electric Charges and Fields

  1. The first set of NCERT Class 12 Exemplar problems, MCQ1, are objective type questions where you need to solve problems on Gauss law, find electric flux and force and come to the correct answer. It has 7 questions.
  2. The second set of NCERT Exemplar problems is MCQ2, has 6 questions based on concepts of Gauss’s law, laws of the electric field, and electric dipole.
  3. The third set of NCERT Exemplar problems requires very short type answers which brush up your knowledge of electric dipole, flux, surface charge density and have 6 questions.
  4. The fourth set of NCERT Exemplar problems are short type answers where you need to apply Coulomb’s law, the equation for the electric field by a system of charges, electric field lines solve the 6 questions provided.
  5. The fifth set of NCERT Exemplar problems involve long answers and hone your expertise on all the topics involved in the discussion of electric charges and fields like Gauss’s law, superposition principle, and properties of electric charges to solve the 6 questions presented.
  6. The NCERT Exemplar questions for class 12 physics chapter 1 give you a strong base for your CBSE as well as many competitive exams like JEE as they are based on many previous year questions as well as questions that appear in competitive exams.

Why Use NCERT Exemplar Class 12 Physics Solutions Chapter 1 – Electric Charges and Fields by Instasolv?

  • Instasolv has used its team of physics experts to provide solutions for the NCERT Exemplar problems on electric fields and charges. 
  • NCERT Exemplar textbooks are a great way to assess your preparedness for any exam.
  • Our solutions will help you in grasping even the complex formulae and in learning how to apply them in easy steps. 
  • To score well in the exam, you should only look up to NCERT Solutions and NCERT Exemplar Class 12 Physics Solutions as they are self-sufficient and cover the entire syllabus of CBSE. 
  • The way these NCERT Exemplar problems are explained lucidly will also help you manage your time in the exam efficiently.