Introduction
Electric Charges and Fields Class 12 Notes deal with the detailed discussion of electric charges and their types. It focuses on Coulomb’s Law, the Superposition Principle, Electric field lines, and their properties. Those concepts are necessary to understand properly how electric forces work.
Definition of Electric Charge
Electric Charge is a fundamental property of matter that can produce and experience the electric and magnetic effects.
Types of Electric Charge
There are two types of electric charge:
- Positive
- Negative
The positive charge is associated with protons, and on the other hand, the negative charge is linked to electrons.
Conductors and Insulators
The substances that allow electricity to pass through them are called conductors, such as metals.
On the contrary, the substances that resist the flow of electricity are the insulators, such as plastic and nylon.
Properties of Electric Charge
Electric charges have three key properties :
- Quantization of Electric Charge— Electric charges come in discrete amounts rather than continuous values. This property implies that electric charges can not be divided into smaller parts.
- Additivity of Electric Charge — The combination of the charges is the algebraic sum of all the individual charges.
- Conservation of Electric Charge — The total charge of an isolated system remains constant over time. Charges can not be created or destroyed, they can only be transferred from one object to another.
Measuring Electric Charge
The unit of electric charge is Coulomb.
One Coulomb refers to the quantity of charge transferred in one second.
Mathematical representation: Q=l.t (Q is the electric charge, l is the electric current, and t is the time)
Coulomb’s Law
The magnitude of the electrostatic force between two point charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance separating them.
If two stationary point charges are Q1 and Q2, and the distance between them is r, and the magnitude of the electrostatic force is F. k is the Coulomb’s constant, then the equation will be, F=kq1q2/r2
Forces between Multiple Charges: Principle of Superposition
Coulomb’s law is applied to the interaction between two charges.
According to the Superposition principle, the interaction between two charges is not influenced by the other charges. In a system, if there are multiple charges present, then the force between two specific charges will remain the same.
Methods of Charging
There are three distinct methods of charging an uncharged object:
- Charging by friction – When two objects are rubbed against each other, charge transfer occurs. One object gains electrons and the other loses.
- Charging conduction– In this process, an uncharged object comes close to a charged object, and if the charged object has an unequal number of protons and electrons, then the uncharged object will discharge electrons to be stable.
- Charging induction– If an uncharged object by merely bringing it close to a charged object without any direct contact. The charged object induces a redistribution of charges in the uncharged object, resulting in the acquisition of charge.
Electric Field
Electric field is a vector field associated with each point in space the force per unit of charge exerted on an infinitesimal test charge at rest at that point.
The SI unit of the Electric field is volt per meter(V/m).
Electric Field Intensity
Electric field intensity can be described as the strength of electric field, that is a vector quantity which describes the force exerted on a unit positive charge placed at a specific point in an electric field.
- It is denoted by “E”
- Electric Field= F/q.
- Unit of E is NC-1 or Vm-1.
Electric Field Lines
A curve drawn through a region of space so that its tangent at any point is in the direction of the electric field vector at that point.
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Properties of Electric Field Lines
- They start from a positive charge and end at a negative charge.
- They do not form a closed loop.
- Two Electric Field Lines never cross each other.
- It shows a continuous curve without having any breakage in a charge-free region. .
Electric Flux
Electric flux is the total number of electric field lines passing through a given area. The electric flux Δθ through a small area element ΔS is given by:
Δθ= E.ΔS= E ΔS cosθ
- E is the electric field strength.
- ΔS is the area element
- Θ is the angle between the electric field E and the normal to the area element ΔS
Electric Dipole
Two point charges of the same magnitude and different nature separated by a small distance form an electric dipole.
Electric Dipole Moment
The strength of an electric dipole can be measured by a vector quantity called the electric dipole moment. The dipole moment is calculated by the product of the magnitude of one of the charges and the distance separating them.
Mathematical expression: p= q x 2 a
P refers to the dipole moment, q is the magnitude of the charge, and 2a is the distance between them.
Gauss Law Formula
According to the Gauss Law, the total charge enclosed in a closed surface is proportional to the total flux enclosed by the surface.
ϕ : Q/ϵ0
Φ: the total flux
Ε0: the electric constant
Q: total electric charge enclosed by the surface
Electric Charges and Fields Class 12 Notes of Learn Physics with Ease are designed to be concise, easy to understand, and also helpful for the students to grasp the key concepts of this chapter. It is one of the well-established coaching centers in Dumdum that offers exam-focused study materials and high-quality practice sets to prepare students for exams. We prepare the notes by experienced educators who are conscious of the needs of the students.
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Conclusion
Understanding the concept of Electric Charges and Fields is important to build an in-depth knowledge of physics. CBSE Electric Charges and Fields Class 12 Notes
Includes a detailed explanation, formulas, and application to help you enhance your comprehension and confidence in the exam.
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