Question

how to know that we have to use formula in physics electrostatic class12​

Answer 1

Explanation:

Electrostatic force

Coulomb's Law

F = kq1q2/r2

where k=1/4πεo=9x109Nm2C-2

εo = 8.85x10-12C2m-2N-1

Answer 2

formulas

Electrostatic force

Coulomb's Law

F = kq1q2/r2

where k=1/4πεo=9x109Nm2C-2

εo = 8.85x10-12C2m-2N-1

See a solved example at

Vector notation

Electrostatic field

Electric field due to a point charge

E = F/qo = kq/r2 N/C

See a solved example at.

E due to circular loop of charge (radius r) at a distance x from the center

Electric dipole

Dipole moment

Cm

Electric field at an axial point of a dipole

Electric field at an equatorial point of a dipole

Torque acting on a dipole in a uniform electric field

Potential energy of a dipole in a uniform electric field

Electrostatic potential

Electrostatic potential difference

Potential due to a point charge

Potential at an axial point of a dipole

if then

Potential at an equatorial point of a dipole

Relation between electrostatic field and potential gradient

Electric field = negative of the potential gradient

Electrostatic potential energy

Electrostatic potential energy of two point charges

Gauss' theorem

Electric flux

Gauss' theorem

Definition: Electric flux ϕ through any closed surface is 1/εo times the net charge Q enclosed by the surface.

Electric field E due to infinitely long straight wire (a line charge)

Electric field E due to thin infinite plane sheet of charge

Electric field between two thin infinite plane parallel sheets of charge

Electric field due to uniformly charged spherical shell

for r > R

for r < R

for r = R

Capacitance

Farad 1F = 1 C/V

Isolated spherical conductor

Parallel plate capacitor

or where and k is dielectric constant

Capacitors in series

Capacitors in parallel

Energy stored in a capacitor

Energy density

Common potential

C with conducting slab between the two plates

where t is thickness of slab [t < d]

C with dielectric slab between the two plates

where k is the