Electricity-The Electric Force

Fundamental Forces

electric force, strong nuclear force, weak nuclear force, gravitational force; these are the only ways that any two things can interact with each other

Electric force

attracts and repels charged particles

Strong nuclear force

keeps protons and neutrons within the nucleus

Weak nuclear force

transforms particles into other particles, involved in radioactive decay

Gravity

pulls mass toward other mass

Gravitational force equation

F=G(m₁m₂/r²)

Gravitational constant

aka Newton’s constant; G=6.67×10^-11 N m²/kg²

Mass of a proton

1.7×10^-27 kg

Mass of an electron

9.1×10^-31 kg

Coulomb’s Law

F=k(q₁q₂/r²); q=amount of charge, k=Coulomb constant

Charge of protons/electrons

±1.7×10^-19 coulombs

Quantized

measured in discrete, countable amounts; charge is quantized

Coulomb constant

k=8.99×10⁹ N m²/C²

Total charge

is conserved and transferred, never created or destroyed; total charge of the universe is 0

Vector

quantity that has both quantity and direction

Scalar

quantity that has only magnitude and no direction

Gravitational force equation (for Earth)

F=mg

Strength of Earth’s gravitational field

g=9.8 N/kg

Electric force equation

F=qE

Electric field

E=how much force a particle with charge q will feel at a certain location; measured in N/C; depends on density of charge and constant Φ_E, not position

Electric field of a proton

points away from it

Electric field of an electron

points toward it

Strength of a proton’s electric field

E=kq/r²

Electric dipole

configuration of positive charge and negative charge close to each other

Gauss’s Law

Φ_E=q/ε₀

Permittivity of free space

ε₀=1/4πk

Electric field flux

Φ_E=EA; amount of electric field passing through a given area; depends on strength of the electric field and the orientation of the area relative to the field

Surface charge density

σ=q/A; amount of charge per area