The 12 most important Formulas:

 The 12 most important Formulas:

Voltage V = I × R = P / I = √(P × R) in volts V

Current I = V / R = P / V = √(P / R) in amperes A

Resistance R = V / I = P / I2 = V2 / P in ohms Ω  

Power P = V × I = R × I2 = V2 / R in watts W