EE 304 - CH1

Card Set Information

EE 304 - CH1
2014-01-04 09:58:02
EE304 circuits

Passive sign convention, basic parameters
Show Answers:

  1. Passive sign convention
    An assumption of: the sign of the current RELATIVE to the voltage for passive circuit elements.

    ASSUME: positive current enters the node at the higher voltage

    ESSENTIALLY:  You can assume (arbitrarily) EITHER the voltage polarity, OR the current direction.  This assumption dictates the assumed direction of the other parameter.  These assumptions provide REFERENCE voltage polarities and current directions.
  2. 3 Steps to assign passive sign convention.  (and what not to do)
    DON'T try to figure out the "correct" voltage polarities or current directions before performing the analysis.

    • 1.  Arbitrarily assign EITHER the assumed voltage polarity OR the current direction.
    • 2.  Label the other characteristic for the passive circuit element so that they agree with the passive sign convention.
    • 3.  Perform the analysis using the assumed signs!  Negative values indicate that the assumption you made was wrong, so switch up the assumed direction of either the current or of the voltage polarity.
  3. How to provided voltage sources affect the choice of the passive sign convention?
    they dont!!!!!!!!!!!!!!!!
  4. Charge
    Charge (q) is the basic quantity in circuit analysis

    Unit:  Coulombs.  1 Coulomb = -6.24 10^18 electrons
  5. Current
    Current (i) is the rate of change of charge with time:

    UNITS: Amperes (coulombs/second)

    i = dq/dt

    If you're sitting at some point in you're circuit and watching electrons go by, the rate at which they're going by gives you the current!
  6. Voltage
    Voltage (v):  Voltage quantifies the change in energy of a unit charge at two different physical locations.

    v = dW/dq

    Units:  Volts (V) => Joules/coulomb
  7. Power
    Power is the rate of change of energy with time

    UNITS: watts

    P = dW/dt = dW/dq x dq/dt = (v)(i) [voltage times current]
  8. Passive Circuit element
    Total energy delivered to the circuit element by the rest of the circuit is non-negative.

    Passive element can STORE or DISSIPATE energy but it cannot CREATE energy.
  9. Active Circuit element
    Active circuit elements can supply energy to the circuit from external sources.
  10. Giga, Mega, Kilo
    Giga = 10^9

    Mega = 10^6

    Kilo = 10^3
  11. Micro, Nano, Pico
    Micro = 10^-6

    Nano = 10^-9

    pico = 10^-12