Rationalize each numerator. See Example 7. 2 - 2116

 Voltage drop across a resistor is always positive.  Power is always dissipated by a resistor.  For loop problems, if the direction of current is given, draw the loops in that direction.  Current flows from higher to lower voltage  When current flows from + to – then power of the source is + (Power is said to be dissipated)  When current flows from – to + then power of the source is – (Power is said to be supplied)  A complete circuit is required for current flow. No breaks.  Diodes and transistors are some examples of components that don’t follow Ohm’s law.  Voltage across elements in parallel are equal  Current across elements in series is equal  For op amp problems, check for negative feedback. Establish V­ = V+ then do a node equation either at v­ o