Question

A model electric train requires 6 V to operate. If the primary coil of its transformer has 240 windings, how many windings should the secondary have if the primary is connected to a 120 V household circuit?

Answer 1

The voltage ratio equals the turns (a.k.a windings) ratio. More turns, more voltage.

120/6 = 240/N

Solve for N.

Answer 2

20=240/N
Is the answer 480=N

Answer 3

120/6 = 240/N
20 = 240/N

(this is where you messed up.
20N=240
N=240/20


N = 240/20
N = 12

Answer 4

Vs = 6 V
Vp = 120 V
Np = 240 turns
Ns = ?

Formula: VpNs = VsNp
Solve for Ns:
Ns = Vs/Vp * Np
Ns = 6/120 * 240
Ns = 0.05 * 240
Ns = 12 turns

Answer 5

An electric doorbell uses 12 V to operate. A transformer powered from a 120 V outlet has 500 turns. How many turns are in the secondary