# Formulas

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

### Ohm’s Law

E = volts
I = current in amps
Z = impedance or resistance in ohms
P = power in watts

### Transformer Input and Output

EPIP = ESIS

EP = primary voltage
IP = primary current in amps
ES = secondary voltage
IS = secondary current in amps

### Capacitive Reactance XC = capacitive reactance in ohms
F = frequency in hertz
C = capacitance in farads

### Inductive Reactance XL = 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

### Secondary Coil Dimensions

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
D1 = outside diameter of toroid in inches
D2 = 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

ERMS = 0.7071·E P

ERMS = RMS voltage
EP = 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

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.