### Ohm's Law

• E = Voltage - measured in Volts
• I = Current - measured in Amperes
• R = Resistance - measured in Ohms
• E = I * R , answer in Volts
• I = E/R, answer in Amperes
• R = E/I, answer in Ohms

### Resistor Networks

• Resistors are labeled by a # following the R : R1...R2...Rn
• Rn = Continues for all the resistors you have.
• Rt = Resistance total
• Resistors in SERIES add : Rt = R1 + R2 +R3....+ Rn

• Two (2) Resistors in PARALLEL : Rt = ( R1 * R2)/(R1 + R2) This the Product divided by the Sum
• More than Two Resistors in PARALLEL: Rt = 1/ (1/R1 + 1/R2...+1/Rn) This is called the reciprocal formula
• Another form of this formula is : 1/Rt = 1/R1 + 1/R2.....+1/Rn

### Inductor Networks

• The rules for Inductors are exactly like those for Resistors
• Inductors are labeled by a # following the L : L1...L2...Ln
• Ln = Continues for all the Inductors you have.
• Lt = Inductance total
• Inductors in SERIES add : Lt = L1 + L2 +L3....+ Ln

• Two (2) Inductors in PARALLEL : Lt = ( L1 * L2)/(L1 + L2) This the Product divided by the Sum
• More than Two Inductors in PARALLEL: Lt = 1/ (1/L1 + 1/L2...+1/Ln) This is called the reciprocal formula
• Another form of this formula is : 1/Lt = 1/L1 + 1/L2.....+1/Ln

### Capacitor Networks

• The rules for Capacitor Networks are exactly opposite for those of Resistors and Inductors.
• Capacitors are labeled by a # following the C : C1...C2...Cn
• Cn = Continues for all the Capacitors you have.
• Ct = Capacitance total
• Capacitors in PARALLEL add : Ct = C1 + C2 +C3....+ Cn

• Two (2) Capacitors in SERIES : Ct = ( C1 * C2)/(C1 + C2) This is the Product divided by the Sum
• More than Two Capacitors in SERIES: Ct = 1/ (1/C1 + 1/C2...+1/Cn) This is called the reciprocal formula
• Another form of this formula is : 1/Ct = 1/C1 + 1/C2.....+1/Cn

### Watt's Law

• P = Power - measured in Watts
• I = Current - measured in Amperes
• E = Voltage - measured in Volts
• R = Resistance - measured in Ohms
• P = I * E, answer in Watts - (easy as "pie")
• P = I*I*R, answer in Watts -( read as I squared R)
• P = E*E/R, answer in Watts -( read as E squared, divided by R)
• Note: Use Ohm's Law to derive other formulas for I , R, and E, using the formulas above.

### Calculating Reactance

• Inductive Reactance

• Pi = = 3.14
• f = Frequency, in Hertz
• L = Inductance of coil, in Henries
• Xl = Inductive Reactance, in Ohms
• Note: Xl is a linear function, it increases as frequency or inductor value increases.

• Capacitive Reactance
• Pi = = 3.14
• f = Frequency, in Hertz
• C = Capacitance in Farads
• Xc = Capacitive Reactance, in Ohms
• Note: Xc is inversely proportional to frequency and capacitance. If either frequency or capacitance increase, Xc decreases.

### Resonance in RLC Series Circuit

#### Frequency and Time

• f is the Frequency in Hertz/Second or Cycles/Second
• t is time in Seconds
• f = 1/t , answer in Hertz/Second or Cycles/Second.
• t = 1/f , answer in Seconds

#### Impedance of a Circuit

• Xc = Capacitive Reactance, in Ohms
• Xl = Inductive Reactance, in Ohms
• R = Resistance, in Ohms
• Z = Impedance, in Ohms
• For a Capacitive circuit

• For an Inductive Circuit

• Rules for when you have a circuit with both Capacitive and Inductive Reactances
• When Xl is larger than Xc use the formula in figure (a) , If Xc is Larger than Xl use the formula in Figure (b).