FORMULA SHELF 1 of 370

The arithmetic behind the work: what to measure, what to type in, and what the answer comes out as. Every formula says what the symbols mean and gives a worked example, so you can check it against a job you have already done.

Quick calculators. A calculator appears where the formula is a single, clean equation with clear symbols. It is a convenience, not an authority: double-check every result yourself, especially doses, loads, torque and safety-critical settings.

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Energy 1 formulas

Ohm's law MOST USED

V = I x R (so I = V / R and R = V / I)

SYMBOLS · V = volts; I = current (A); R = resistance (ohms)

UNITS · V, A, ohm

HOW TO USE

The starting point for any electrical fault finding. If the voltage is right and the lamp is dim, the current is low, so the resistance is too high. See Electrical Fault Finding.

EXAMPLE

12 V across a 6 ohm lamp draws 2 A.

QUICK CALCULATOR V = result

I current (A) R resistance (ohms)

Enter values above.

Convenience only. Double-check the result against the worked example or a second method before you use it.

electricity ohm voltage current resistance

SOURCES & PROVENANCE 1 listed

This page is an AI-organised index. The label means the grouping and cross-links were compiled with AI; the information itself comes from the public-domain books, reports and manuals listed below. Open any source to read the local copy or follow the link to the original publication.

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The index is AI-organised; the linked sources are not.

Formulas collected and indexed with AI. The calculators are convenience tools; double-check every result before using it.