Ideal transformer rows close both power and energy ledgers. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Two-to-four turns doubles voltage
Turns 2 to 4 double voltage from 4 V to 8 V. Primary power 16 W over 3 s gives energy 48 J.
4×4=16,E=16×3=48
Three-to-six turns keeps power balanced
Turns 3 to 6 double voltage from 6 V to 12 V. Primary power 12 W over 5 s gives energy 60 J.
6×2=12,E=12×5=60
Four-to-eight turns also closes energy
Turns 4 to 8 double voltage from 8 V to 16 V. Primary power 16 W over 4 s gives energy 64 J.