Sparky's Journal
Sparky's Journal
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📅 March 18, 2026
Ohm's law and the Power (watts) Wheel are key formulaic methods commonly used by Electricians for various calculations encountered in the electrical field. This makes understanding the fundamentals a key priority for studying apprentices.
Let's begin with the principles of Ohm's law, published by German physicist Georg Simon Ohm in his 1827 “The Galvanic Circuit Investigated Mathematically” titled book, describing the law of his discoveries on the relationship of (E)voltage also known as (V)Volts discovered by Alessandro Voltas invention of the voltaic pile, the first battery, (I)current also known as (A) Amperage discovered by Andre-Marie Ampere when learned electrical currents create magnetic fields inspired by another physicist Hans Christian Oersted, and (R)resistance also known as the (Ω)Ohm which the symbol is an ode to. Inspired by the discovery of electromagnetism and experiments using voltaic piles (alternating disks of different metals, separated by material soaked in electrolytes), wires, and a galvanometer (a tool that detects and measures small electric currents by deflecting light beams). Over a few years, he realized that current is directly proportional to voltage and inversely proportional to resistance. Applying mathematical formulae to this, his theory of the equation V = I x R (Voltage = Current x Resistance) was discovered.
Finally The (W)Watt or (P)Power the rate at which energy is produced, named after the Scottish mechanical engineer James Watt, who primarily improved steam engines, and discovered the unit horsepower, which is 746 watts (1 horsepower)
All thanks to Michael Faraday's research on electromagnetic induction.
How to write the basic Ohms Wheel (left) and Power (right)
Draw an elementary circuit diagram
and write “RIPE” in a column
Now, the given values are in both the “RIPE” column and the diagram.
Select the appropriate formula and write it down.
P = I x E
Substitute the given values into the formula.
P = I x E (12A x 120V) =
Solve
P = I x E (12A x 120V) = 1,440W
Write in the answer next to your “RIPE” column; don't forget to label your work to avoid confusion.
Using the same method, just with a different formula, solve for the last unknown.
SERIES CIRCUITS
It = I1 = I2 = I3, and so on. Current Stays The Same.
Et = E1 + E2 + E3, and so on, Voltage Increases.
Rt = R1 + R2 + R3, and so on, Resistance Increases.
Pt = P1 + P2 + P3, and so on, Power Increases.
PARALLEL CIRCUITS
It = I1 + I2 + I3, and so on, Current Increases.
Et = E1 = E2 = E3 and so on, Voltage Stays The Same.
Pt = P1 + P2 + P3, and so on, Power Increases.
When there is an equal number of resistors.
(where R = the value of each resistor, and N = the number of resistors)
When there are only TWO resistors.
When there are THREE OR MORE UNEQUAL resistors.
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