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# Xam Idea Class 12 Physics Chapter 1 Solutions: Electric Charges And Fields

Xam Idea Class 12 Physics Solutions for Chapter 1 ‘Electric Charges and Fields’ is a perfect guide for CBSE Class 12 exams preparation. These solutions will help you learn about electric fields, types of electric charges, Coulomb’s law, electric dipole, properties of electric charge, properties of the electric field and electric fields due to the system of charges.  You will also study about Gauss’ law, application of Gauss’ law, electric flux and the superposition principle.

Xam Idea solutions for Electric Charges and fields have 81 questions divided into 4 exercises. These include short answer questions, long answer questions, very short answer questions and very long answer questions. You will be solving problems related to electric field lines, electric fields due to an electric dipole, the force exerted by the electric field on different bodies, and continuous charge distribution. Some questions also include the different types of SI and CGS units.

Instasolv’s Xam Idea Class 12 Physics solutions equip you with time management tricks and tips and clear out all doubts related to the chapter. You will be able to solve the most complex problems in an easy way and in the shortest time frame. Furthermore, our solutions by Instasolv will prepare you with the right tricks and key points to remember before going to any exam.

## Important Topics for Xam Idea Class 12 Physics Solutions Chapter 1: Electric Charges and Fields

The thorough ideas presented in Xam Idea Class 12 Physics book Chapter 1: Electric Charges and Field will teach you how to derive electric field due to different kinds of charges and how to solve numerical on the electric field, electric charges, and Gauss’ law.

• Electric Charge

Electric charge is the physical property of matter that causes it to experience a force on it whenever it is placed in an electromagnetic field. We mainly have two categories of electric charges: positive charge and negative charge. We already know that like charges repel each other and unlike charges attract each other. Unit is Coulomb (C).

• Methods of charging a body
1. By direct contact – when a charged body is brought in contact with another charged or neutral body, some charge is transferred between the two bodies. The actual charged body loses some charge in this case.
2. Induction method – when a charged body is brought near to another neutral or charged body but not kept in touch, some charge is induced in the second body. It can be of the same polarity or even the opposite. In this case, none of the bodies loses any charges.
• Properties of electric charge
2. Conservation of charges
3. Quantization of charges
• Coulomb’s law

Coulomb gave three laws about electric charges known as Coulomb’s law. The three postulates of this law state that the force exerted between two point charges is:

1. Directly proportional to the product of the magnitude of the two electric charges
2. Is inversely proportional to the distance (or separation) between the two-point charges.
3. The force acts along the line joining the centre of the two-point charges
• Superposition Principle

As per the principle of superposition given for the electric charges, the force on any point charge due to a number of other charges in its vicinity is given by the vector sum of all the forces on that charge due to the other charges, taken one at a time.

• Electric Field

The region around an electric charge where other electric charges may experience a force if they are inside the field is called electric field due to an electric charge which is a vector quantity. Unit is Newtons per Coulombs (N/C).

• Electric Field Lines

An electric field line is a curved line drawn in such a way that the tangent to it at any point on the line points in the direction of the net electric field at that point.

• Electric Flux

Electric flux is a measure of the flow of the electric field through a given area. Electric flux is directly proportional to the number of electric field lines going through a normally perpendicular surface. Unit is NC-1m2

• Electric Dipole

An electric dipole is defined as a pair of equal charges but oppositely charged point charges q and –q, separated by a distance of 2a. The total charge of an electric dipole is zero however the electric field due to an electric dipole is not zero. The dipole moment is calculated by the formula 2a X q.

• Electric Field due to an Electric Dipole

The electric field at any point in space due to an electric dipole depends on the position of the point in space that we are considering.

• Gauss’ Theorem

According to Gauss’s law of electrostatics, the total (sum) of the electric flux out of a closed surface is equal to the charge enclosed by the surface divided by the permittivity of space. If no charge is enclosed by a closed surface, the total electric flux through it is zero.

• Application of Gauss’ Theorem

Gauss’ law is used to calculate the electric field in the following cases:

1. i) Electric Field due to an infinitely long straight wire of uniform charge distribution
2. ii) Electric field due to an infinitely long plane sheet of uniform charge distribution

iii) Electric field due to a thin spherical shell of uniform charge density

Using these concepts, there are several sums where you will be asked to derive the expression of the electric field due to a particular body of electric field of uniform charge density.

### Discussion of Exercises for Xam Idea Class 12 Physics Solutions Chapter 1: Electric Charges and Fields

VSAQ portion has a total of 26 questions divided into two sections PYQ (previous year questions) and OIQ (objective inventory questionnaires) having 13 each. These questions mostly cover the portions of the superposition principle, electric field, electric field lines, Gauss’ law and some numerical on an electric charge.

SAQ – I (Short Answer Questions – I)

SAQ – I portion has a total of 25 questions divided into two sections (PYQ and OIQ) – each section having 13 and 12 questions respectively. These questions mostly cover the portions of the superposition principle, electric field, electric field lines, conceptual derivations, Gauss’ law, application of Gauss’ law, Energy density and some numerical on an electric charge. This portion mostly consists of numerical and derivations however some theoretical questions are also present.

SAQ – II (Short Answer Questions – II)

SAQ – II portion has a total of 20 questions divided into two sections (PYQ and OIQ) – each consisting of 11 and 9 questions respectively. These questions are based on the electric field, electric field lines, the force exerted by the electric field on a body, principle of superposition, Gauss’ law, derivations and numerically based on the application of Gauss’ law and some numerical on electric charge as well.