Formula Library

The calculations behind the trades - each formula links to its mathematics module and to the games where it is applied.

V = I x R

The foundation of electrical circuit work: voltage equals current times resistance. Rearranges to I = V / R and R = V / I.

P = V x I

Power delivered by a circuit: voltage times current. Also P = I² x R for resistive loads, showing why current is the enemy of wiring.

P = sqrt(3) x V x I x PF

Real power in a three-phase system. Rearranged, it estimates motor full-load current - the value compared with clamp-meter readings.

Vp / Vs = Np / Ns

Primary to secondary voltage equals the turns ratio. Current scales inversely: the low-voltage side carries the high current.

Q = V / t

Volume moved per unit time - the heartbeat of pumps, pipes and treatment processes. Velocity follows as v = Q / A.

P = rho x g x h

Pressure from a liquid column: density times gravity times height. Every 10 m of water adds about 98 kPa.

eta = P_hydraulic / P_input

Hydraulic work delivered divided by power consumed. Falling efficiency at constant flow signals wear.

f = RPM / 60

Shaft rotation frequency in hertz - the anchor for 1x, 2x and 3x vibration references.

V = pi x r^2 x h

Tank and pipe capacity. Remember: radius is half the diameter - using the diameter squares the error.

t = V / Q

How long a tank holds liquid before it moves on - the budget for disinfection, settling and reactions.

Loading% = actual / rated x 100

Equipment load versus rating - the operating judgement between underloaded, sweet spot and pushed too hard.

takt = available time / demand

The pace the line must keep to meet demand - the number that exposes bottlenecks instantly.