Direct Current I = Current in Amperes (Amps) V = Voltage (or Potential Difference) in Volts R = Resistance in Ohms W = Power in Watts I = V/R and V = IR and R = V/I W = I2R and W = V2/R and W = VI The above hold good for Alternating Current only if the load is purely resistive (rare). Resistances in Series: R = R1 + R2 Resistances in Parallel: 1/R = 1/R1 + 1/R2 Gain or Loss Gain or Loss = 10 Log (Output Power/Input Power) = 10Log (P2/P1) or = 20 Log (Output Current/Input Current) = 20 Log (I2/I1) or = 20 Log (Output Voltage/ Input Voltage) or = 20 Log (V2/V1) e.g. Power Ratios : 2 x = 3 dB approx. 4 x = 6 dB approx. 8 x = 9 dB approx. 10 x = 10 dB 100 x = 20 dB 1,000 x = 30 dB 1,000,000 x = 60 dB |
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