Source: http://teslacoils4christ.org/TCFormulas/TCFormulas.htm#capreac

### Ohm’s Law

E = IZ | P = IE |

E = volts

I = current in amps

Z = impedance or resistance in ohms

P = power in watts

### Transformer Input and Output

E_{P}I_{P} = E_{S}I_{S}

E_{P} = primary voltage

I_{P} = primary current in amps

E_{S} = secondary voltage

I_{S} = secondary current in amps

### Capacitive Reactance

X_{C} = capacitive reactance in ohms

F = frequency in hertz

C = capacitance in farads

### Inductive Reactance

X_{L} = inductive reactance in ohms

F = frequency in hertz

L = inductance in henrys

### Resonant Circuit Formula

F = frequency in hertz

L = inductance in henrys

C = capacitance in farads

### Spiral Coil Inductance

L = inductance of coil in microhenrys (µH) R = average radius of the coil in inches N = number of turns W = width of the coil in inches |

### Helical Coil Inductance

L = inductance of coil in microhenrys (µH) N = number of turns R = radius of coil in inches (Measure from the center of the coil to the middle of the wire.) H = height of coil in inches |

### Inverse Conical Coil Inductance

L = inductance of coil in microhenrys (µH) L _{1} = helix factorL _{2} = spiral factorN = number of turns R = average radius of coil in inches H = effective height of the coil in inches W = effective width of the coil in inches X = rise angle of the coil in degrees |

### Secondary Coil Dimensions

T = AH |

L = length of wire in feet

D = outer diameter of coil form in inches

H = height of windings in inches

A = number of turns per inch

T = total number of turns

B = thickness of wire in inches

### Medhurst

C = self capacitance in picofarads

R = radius of secondary coil in inches

L = length of secondary coil in inches

### Toroid Capacitance

C = capacitance in picofarads

D_{1} = outside diameter of toroid in inches

D_{2} = diameter of cross section of toroid in inches

This equation courtesy Bert Pool.

### Sphere Capacitance

C = capacitance in picofarads

R = radius in inches

### Plate Capacitors

C = capacitance in microfarads

K = dielectric constant

A = area of each plate in square inches

N = number of plates

D = distance between plates in inches (thickness of dielectric)

### Leyden Jar Capacitors

C = capacitance in microfarads

K = dielectric constant

D = diameter of jar in inches

H = height of jar in inches

T = thickness of jar in inches

### AC RMS and Peak Voltage

E_{RMS} = 0.7071·E _{P}

E_{RMS} = RMS voltage

E_{P} = peak voltage

### Rotary Spark Gap Firings per Second

F = firings per second (hertz)

R = motor RPM rating

E = number of rotary electrodes

### Rotary Spark Gap Electrode Speed

S = electrode speed (MPH)

R = motor RPM rating

D = diameter of electrode placement circle (inches)

### Energy for L and C

Capacitance | Inductance |

J = 0.5 V^{2} C | J = 0.5 I^{2} L |

J = joules of energy stored

V = peak charge voltage

I = peak current

C = capacitance in farads

L = inductance in henries

Peak values of V and I are stated in order to emphasize not to use RMS values. The energy stored at any given time is of course: J(t) = 0.5 [V(t)]^{2} C and J(t) = 0.5 [I(t)]^{2} L.