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Basic Physics

Ohms Law, Power Law and Battery Capacity.
We need to know that power (watts) is voltage (volts) times current (amps). Power (watts) is also energy (joules) per unit time (second).

And a joule of energy is one colomb of charge dropping one volt in potential.

P = V x I = E x f

We also need to understand a little about capacitance. A capacitor stores energy. The wiring capacitance for a pair of conductors, surrounded by silicon dioxide (permitivity 4), is Pi * e_0 * e_r in Farads per metre, which is roughly 100 pF/m. This applies fairly well for VLSI nets where the units of 0.1 pF/mm or 0.1 fF/um are more useful.


2: (C) 2008-18, DJ Greaves, University of Cambridge, Computer Laboratory.