The magnet dataset is from an experiment concerning the magnetic force of an electomagnet as a function of voltage and number of wire turns. The device was a wire wrapped around a core and measured at a variety of voltages. The statistical design here is actually a randomized complete block design where the three eletromagnets are the blocks, and the three voltages are levels of the factor voltage.
Voltage applied (1.5 or 3.0 volts).
The number of wire turns (100, 200, or 300, as factors).
The magnetic force.