← (ne02) Electric Charges and Forces →
Models
- Particle (Energy + Mass Movement)
- Wave (Energy Transfer)
- Field (NEW way of thinking: Faraday!)
From Forces to Fields:
$$ F_g(r) = K_g \, { \color{fuchsia}{m} M \over r^2} \, [N] \, = \color{fuchsia}{m} \, { K_g M \over r^2} \,$$
→ Fg(r=6351km) = m g
(g is the strength of the gravitational field on earth's surface [N/kg] (r=6371km))
Similarily...
$$ F_e(r) = {1 \over {4 \pi \epsilon_o}} \, { \color{fuchsia} {q} Q \over r^2} \,\, [N] \,\,\,\, Coulomb's \, Law $$
$$ F_e(r) = {{1 \over {4 \pi \epsilon_o}} \, { \color{fuchsia} {q} Q \over r^2} \,
= \, \color{fuchsia} {q} \, {1 \over {4 \pi \epsilon_o}} {Q \over r^2 } \,
= \, \color{fuchsia} {q} \, E(r) \,\, }
$$
Thus Fe(r) = q E(r) and E(r) has units [N/C]
$$ E(r) = {1 \over {4 \pi \epsilon_o}} \, { Q \over r^2} \,\, [N/C] $$
PBL Highlights (30 min)
History Knight-v4 ch 22.1 → 22.3
Video: Professor Julius Sumner Miller on Electrostatic Phenomena
Coulombs Law (Knight ch2.4)
Concept of Electric Field (Knight ch2.4)