Coulomb's Law

Coulomb's Law

Any two point charges exert an electrical force on each other that is proportional to the product of their charges and inversely proportional to the square of the distance between them

the law states that

Electric fields

An electric field is a field of force and can be represented by field lines.
The electric field strength at a point is the force per unit positive charge that acts on a stationary charge

Field strength= force/charge=potential difference/seperation

According to Coulomb's Law, Force is directly proportion to the product of the charges and inversely proportionate the square of the distance

This gives us the mathematical equation F=(K*Q1Q2)/r^2

However there is a constant involved, K= 1/4pi epsilon (e) which has an approximate value of 9.0*10^9 Nm^2/C^2

This gives us the final equation for power=(Q1Q2)/4pi e*r^2

Electric Field Strength on a point mass in an electric field is given by the equation E= Q/(4 pi e*r^2)

Potential difference is defined as the energy change per coulomb between two points, hence W=QV

Energy in a radial field is given by the equation V=Q/(4pi e* r)= -GM/r

Comparison

Gravitational fields

Electric fields

arise from masses

arise from electric charges

field strength g = F/m

field strength E = F/Q

parallel gravitational field lines g = constant

parallel electric field lines E = V/d = constant

radial field lines
force given by Newton’s law

radial field lines
force given by Coulomb’s law

potential obeys an inverse relationship with distance and is zero at infinity
potential is a scalar quantity and is always negative

potential obeys an inverse relationship with distance and is zero at infinity
potential is a scalar quantity