Electrostatics
Properties of charges
Charges exert force
Charges are quantized
Charges are conserved
Coulomb's Law
Definition
The attractive force or the repulsive force of two point charges is directly proportional to the magnitude of the two point charges and inversely proportional to the distance of the two point charges squared.
Formula
Important Notes
Notes
Coulombs's law force is vector
The sign is not inserted into Coulomb's law equation
The net force is vector sum which consideration of direction
Conductors and Insulators
Important Key Points
Conductors
Able to conduct
Have free electrons not tightly bounded to atoms
The Electric field inside the conductor is zero
The charges reside on the surface
The Electric field is perpendicular to the surface
High concentration of charges on high curvature
Insulators
No free electrons, tightly bounded to atoms
able to conduct but very little
How to acquire charges? How to release charges?
Charging
Induction, net charge=0
Grounding
Discharging
Grounding
Contact
Contact/ Conduction
Electric Field
Definition
The electric field strength is defined in a field as the force exert on a point charge by a test charge by a distance of separation.
Formula
Important Notes
Notes
Electric field is a vector
The sign is not inserted in Electric field equation
The net electric field is vector sum
Electric dipole
Happens when charges of equal magnitude but opposite sign
Formula
Charge densities
Gauss Law
Definition
The net electric flux is directly proportional to the net electric charge passing through any enclosed space.
Formula
General
Line
Sphere
Electric Potential
Work
Equipotential Surface
Surface where the electric potential is same on every point
Electric field perpendicular to the equipotential surface
Same as electrical potential energy
Work done positive = with the flow of electric field
Work done negative = against electric field
Net work done/ electric potential energy= algebraic sum due to other point charges on the test charge
Definition
Work done to bring a charge from a point to another point
Formula
Electric potential only depends on final and initial position of a particle regardless of the path taken
Important Notes
Net electric potential on a test charge due to other point charges is the algebraic sum
Even though electric field is zero inside a conductor but the electric potential is constant in the range of radius of conductor
Electric field and electric potential relation
Sphere
Plates