Changing flux sets voltage size, while the sign of change sets polarity. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Small increase gives two volts
Flux goes from 2 Wb to 8 Wb, so change size 6 Wb over 3 s gives 2 V and polarity opposes the increase.
V=∣8−2∣/3=2
Larger increase gives four volts
Flux goes from 2 Wb to 14 Wb, so change size 12 Wb over 3 s gives 4 V and polarity opposes the increase.
V=∣14−2∣/3=4
Equal-size decrease keeps magnitude and flips polarity
Flux goes from 14 Wb to 2 Wb, so change size 12 Wb over 3 s gives 4 V and polarity opposes the decrease.