1. In an isolated system, the charge is always conserved. 2. Protons and electrons have a quality called electric charge. 3. The charge is invariant in nature. 4. The charge is quantized.
* ***(Q = n e)*** * e = 1.6 \* 10^-19 C
* n = no. of electrons * Q = charge
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Ionisation
It involves addition or removal of electrons.
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Coulomb’s Law
The electric force between two particles with charges q1 and q2 separated by distance r has a magnitude by the equation:
***F = Kq1q2/r^2***
* F = force * K = coulomb’s constant * q1 and q2 = charges * r = distance between the charges
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Addition of forces
Consider three point charges: q1, q2, and q3. The total electric force acting on, say, is simply the sum of F1-on-2, the electric force on q2 due to q1, and F3-on-2, the electric force on q2 due to q3:
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Electric Field
The space is surrounded by a charge in which another charged particle experiences the force.
***E = F on q/ q***
It describes the electric field vector from the force vector on a positive charge.
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Electric field due to a point charge
The electric field surrounding the point charge is:
***E = 1/4πε0 * Q/r^2***
* E = electric field * Q = charge * r = distance between charges * ε0 = permittivity of free space
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Three types of electric field
* Radial field * It is generated by a collection of point charges. * An infinite sheet of charge.
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electric field lines
* The electric fields follow the same addition properties as the electric force. * The electric field lines never cross.
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The uniform electric field
* A lot of problems deal with the uniform electric field. * The field may be taken as uniform at least in the middle. * The uniform field just signifies the constant force.
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Conductors
Materials which allow the flow of excess charge without resisting it.
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Insulators
Materials that resist the flow of electrons.
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Charging by friction
It involves rubbing the insulator against another material, thereby stripping electrons from one to another material.
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Charging through conduction
When we connect two conductors charge flows from one to another until the potential of both the conductors becomes the same.
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Charging through induction
The process of charging by induction may be used to redistribute charges among a pair of neutrally charged spheres.
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If the sphere is an insulator made up of glass
* There aren’t any free electrons. * The atoms make up the sphere will become polarised.
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charge of proton
positive
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charge of electron
negative
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law of charges
the directions of the electric forces on the charges of mutual interaction; like charges repel, opposite charges attract.
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net charge
an object with an excess of positive or negative charges
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electrostatic charging
accomplished by Friction, Contact, Induction, or Polarization
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Charging by Polarization
Charging by Polarization
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How do objects become charged?
By gaining/losing electrons
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Electric charge is always _______.
Conserved
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What is the numerical value of one charge?
1 e = 1.6 x 10^-19 Coulombs
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The SI unit of a charge is in ______.
coulombs
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What happens when an insulator is charged?
Only the small spot which was directly contacted with a charge remains charged.
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What is the name of materials that contain properties somewhere between conductors and insulators?
semiconductors
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A dipole consists of:
two equal and opposite charged
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In what direction to field lines go?
From positive to negative charges ALWAYS
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What indicated field strength?
The density of field lines
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What do few field lines between charges indicate?
a weak field
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Which one of the following rules, laws, or principles describes how the net electric charge of an isolated system undergoing any process remains constant?