Elec Class
learn electricity hands-on
Solved exercise · level 2 of 5
Skills: Calculate
A roadworks warning light draws an average current of 0.5 A. It is powered by a cell of usable capacity 4.5 Ah. For how long (in hours) does it run without interruption?
Q = 4.5 Ah · I = 0.5 A
Parametric exercise: the values change with every draw; these are one example.
Guided problem in 4 steps: unknown, formula, units, data, result.
t = Q / I = 4.5 / 0.5 = 9 h.