Basic Electrical Engineering (part-2)

Basic Electrical Engineering

Basic Electrical Formula:

The most common used electrical formulas – Ohms Law and combinations. Common electrical units used in formulas and equations are

Electrical Voltage – Ohm’s Law

Ohm’s law can be expressed as:

V = R I                        (1a)

V = P / I                      (1b)

V = (P R)1/2                (1c)

Electric Current – Ohm’s Law

I = V / R                      (2a)

I = P / V                      (2b)

I = (P / R)1/2               (2c)

Electric Resistance – Ohm’s Law

R = V/ I                     (3a)

R = V2/ P                   (3b)

R = P / I2                   (3c)

Electric Power

P = V I                      (4a)

P = R I2                    (4b)

P = V2/ R                  (4c)


P = power (watts, W, J/s)

V = voltage (volts, V)

I = current (amperes, A)

R = resistance (ohms, Ω)

Electric Energy

Electric energy is power multiplied with time:

W = P t                       (5)


W = energy (Ws, J)

t = time (s)

Alternative – power can be expressed

P = W / t                     (5b)

Power is consumption of energy by consumption of time.


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