Studied by 4 people
It deals with electric charges and fields associated with it.
Electric Charge
In an isolated system, the charge is always conserved.
Protons and electrons have a quality called electric charge.
The charge is invariant in nature.
The charge is quantized.
(Q = n e)
e = 1.6 * 10^-19 C
n = no. of electrons
Q = charge
Ionisation
It involves addition or removal of electrons.
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
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:
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.
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
Three types of electric field
Radial field
It is generated by a collection of point charges.
An infinite sheet of charge.
electric field lines
The electric fields follow the same addition properties as the electric force.
The electric field lines never cross.
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.
Conductors
Materials which allow the flow of excess charge without resisting it.
Insulators
Materials that resist the flow of electrons.
Charging by friction
It involves rubbing the insulator against another material, thereby stripping electrons from one to another material.
Charging through conduction
When we connect two conductors charge flows from one to another until the potential of both the conductors becomes the same.
Charging through induction
The process of charging by induction may be used to redistribute charges among a pair of neutrally charged spheres.
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.
charge of proton
positive
charge of electron
negative
law of charges
the directions of the electric forces on the charges of mutual interaction; like charges repel, opposite charges attract.
net charge
an object with an excess of positive or negative charges
electrostatic charging
accomplished by Friction, Contact, Induction, or Polarization
Charging by Polarization
Charging by Polarization
How do objects become charged?
By gaining/losing electrons
Electric charge is always _______.
Conserved
What is the numerical value of one charge?
1 e = 1.6 x 10^-19 Coulombs
The SI unit of a charge is in ______.
coulombs
What happens when an insulator is charged?
Only the small spot which was directly contacted with a charge remains charged.
What is the name of materials that contain properties somewhere between conductors and insulators?
semiconductors
A dipole consists of:
two equal and opposite charged
In what direction to field lines go?
From positive to negative charges ALWAYS
What indicated field strength?
The density of field lines
What do few field lines between charges indicate?
a weak field
Which one of the following rules, laws, or principles describes how the net electric charge of an isolated system undergoing any process remains constant?
law of conservation of electric charge
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