Linear Circuits 1

8/19

  • DC Analysis

    • Direct current

    • Current will flow only in one direction, and will have a constant magnitude

    • DC sources like batteries provide steady state voltage (constant voltage) between the two terminals

    • Ohm’s Law, V=IRV=IR, v is voltage, I is current, and R is resistance value

  • AC Analysis

    • Alternating Current

    • Current is changing direction periodically

    • Generated by rotating machines called alternators

    • i(t)=v(t)Ri\left(t\right)=\frac{v\left(t\right)}{R}

  • Passive Components

    • Resistor (R)

    • Capacitor (C)

    • Inductor (L)

  • Standard Units

    • Voltage - Volts - V

    • Current - Amperes - A

    • Power - Watts - W

    • Energy - Joules - J

  • Metric Prefixes

    • Pico - 10−1210^{-12} - pV, pA, pW

    • Nano - 10−910^{-9} - nV, nA, nW

    • Micro - 10−610^-{6} - µV, µA, µW

    • Milli - 10−310^{-3} - mV, mA, mW

    • Kilo - 10310^{3} - KV, KA, KW

    • Mega - 10610^{6} - MV, MA, MW

  • Current and electrons

    • Current is due to the flow of electrons (e−e^{-})

    • -         e−e^{-}         +

                 →

    • - Current +

      ←

    • e−e^{-}: q=1.6⋅10−19q=1.6\cdot10^{-19} C

    • 1C=6.24⋅10181C=6.24\cdot10^{18} electrons

    • Current = rate of charge flow per unit of time dqt=dt(q)=i\frac{dq}{t}=\frac{d}{t}\left(q\right)=i

      • I=flow of electric charge per unit time dqt\frac{dq}{t}

    • Voltage = rate of change of energy per unit charge dq(w)\frac{d}{q}\left(w\right)

    • Power = Rate of change of energy with time P=dwt=dwq⋅dqtP=\frac{dw}{t}=\frac{dw}{q}\cdot\frac{dq}{t}

      • P=VIP=VI Watts

  • Two scenarios of Power:

    • Power absorbed

    • Power delivered