Current, Charge and Potential Difference
- Current = rate of flow of charge. Depends on drift velocity (av. v of electrons). Can measurewith ammeter in series.
- varies with no. charge carriers, cross-sectional area of wire, speed of charge carriers and the amount of charge they carry. from thus, we derive I = nevA. e = amount of charge: 1.6*10^-19. (q = charge)
- Coulombs = unit of charge; 1 amp per second.
- Different materials vary in no.s of charge carriers. In metals = free electrons. semi-conductors have less carriers than metals. insulators have few carriers as possible.
- In liquids/gases, carriers = ions. ionic crystals like NaCl don't conduct when solid, do when molten.
- Gases insulators until v. high P.D., when electrons ripped from stoms making spark.
- For charge to flow, must do work. p.d. = energy per unit charge moved in volts. V = W/Q. 1v = 1JC^-1
- Created by: Ellen
- Created on: 09-03-14 12:09
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