PHYS 1B Chapter 21: Textbook Notes
Document Summary
Phys1b textbook notes chapter 21: current and direct current circuits. Electric current exists when charge is flowing: mathematically: current is the rate at which electric charge flows through the surface instantaneous current i is the limit, si unit of current: ampere (a) Vd = drift speed (average speed of charge carrier along the wire: average current in the conductor: Units: a/m2 (cid:1006)(cid:1005). (cid:1006) resista(cid:374)(cid:272)e a(cid:374)d oh(cid:373)"s law. Oh(cid:373)"s la(cid:449): resista(cid:374)(cid:272)e is (cid:272)o(cid:374)sta(cid:374)t o(cid:448)er a (cid:449)ide ra(cid:374)ge of applied (cid:448)oltages for (cid:373)a(cid:374)(cid:455) materials: ohmic materials: materials that obey the law, nonohmic materials: materials that do not obey the law. Constant of proportionality p is the resistibity of the material (ohm*meter) Energy transformed to internal energy from increased vibrational motion of atoms in the resistor: net result: Some chemical energy in battery is delivered to resistor and resides in resistor as internal energy associated with molecular vibration increased temperature causes transfer of energy by heat into the air.
