PHYS 1750: SELECTED TOPICS in PHYSICS
LECTURE 31. Currents, Resistance, and Power
| 19.1. | Electric Current | ||
| 1. | Total flow of charge I = Q /Δ t | ||
| 2. | Ampere = Coulomb/second | ||
| 3. | Pos = positive charge/second | ||
| 4. |
Charge in volume Q = n*A*Δ x*q n = number of charges / unit volume A = cross section area of current flow Δ x = length of current flow q = charge value of charge carriers (electrons) | ||
| 5. | Δ x = v*Δ t; v = drift velocity | ||
| 6. | I = n*q*v*A | ||
| 19.2. | Resistance R | ||
| 1. | Ohm's law: Δ V = IR | ||
| 2. | Ohm = Volt/Ampere = Joule*second | ||
| 19.3. | Resistivity ρ (bulk property) | ||
| 1. | R = ρ*L /A | ||
| 2. | Materials (Table 19.1) | ||
| 19.4. | Energy and Power | ||
| 1. | P = IV | ||
| 2. | P = I 2R | ||
| 3. | P = V 2/R | ||