Chapter 2. Maxwell’s First Law

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1. Maxwell’s First Law (Gauss’s Law for Electricity)

⑴ Definition : Electric field is created when there is a charge

① (Reference) Circuit theory is related to Gauss’s law for electricity

⑵ Mathematical expression : Using divergence theorem

① D is referred to as electric flux density

② The integral of the electric field along a Gaussian surface surrounding the charge is equal to the charge divided by the permittivity in space

⑶ Example 1. Electric field and potential at a distance r from the center of a point charge with charge q (Coulomb’s Law)

⑷ Example 2. Electric field and potential of a uniformly charged infinite straight conductor with linear charge density λ (C/m)

⑸ Example 3. Electric field and potential of a uniformly charged infinite plane conductor with surface charge density σ (C/m²)

⑴ Definition : State where two point charges with opposite polarities are fixed at a distance d apart

⑵ Dipole moment is represented by the arrow ⤉

① In physics, the direction of the dipole moment is (-)pole → (+)pole

② In chemistry, the direction of the dipole moment is (+)pole → (-)pole, reflecting the atomic structure with a nucleus at the center

⑶ Potential due to a dipole

① V(r, θ) : Potential at a location with distance r from the center of the electric dipole and an angle θ with the direction of the dipole moment

② Assumption : r is much larger than d

③ V(r, θ) inversely proportional to r² and directly proportional to cos θ : Different from the general potential that inversely depends on r

Input : 2022.04.23 19:24