PHYS 1B Lecture 14: Notes
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If n unknowns (currents/voltages you are asked to find), you need n equations: use junction rule on as many junctions as you like, but each should contain at least 1 current that has(cid:374)"t (cid:271)ee(cid:374) used i(cid:374) p(cid:396)e(cid:448)ious ju(cid:374)(cid:272)tio(cid:374) If r is too lo(cid:449), the (cid:272)u(cid:396)(cid:396)e(cid:374)t i = v/r (cid:449)ill (cid:271)e too high and gel will heat up and melt. If r is too high, the current will be too low and dna will move too slowly. Clicker question: which is not true about resistors: a) the resistance of a resistance is independent of current. *resistance is constant; the current cha(cid:374)ge (cid:272)auses v (cid:272)ha(cid:374)ge: b) resistivity depends only on the properties on the material from which a resistor is made, not the size and shape of the resistor. *(cid:396)esisti(cid:448)it(cid:455) (cid:396)esista(cid:374)(cid:272)e. resista(cid:374)(cid:272)e itself depe(cid:374)ds o(cid:374) the size a(cid:374)d shape, (cid:271)ut resistivity (p) depends on the properties of the material: c) when current flows through a resistor, potential energy increases.
