The ratio of the secondary to primary voltages in a transformer equals the ratio of the number of loops in their coils, i.e. [math]\frac{V_S}{V_P}=\frac{N_S}{N_P}[/math].
Assuming that resistance is negligible, the electrical power output of a transformer equals its input. [br]Hence, [math]\text{ $P_P = I_PV_P = I_SV_S = P_S$}[/math].[br][br]Rearranging, we have[br][br][math]\frac{V_S}{V_P}=\frac{I_P}{I_S}[/math][br][br]Also,[br][math]\frac{I_S}{I_P}=\frac{N_P}{N_S}[/math]
A travel adapter has a step-up transformer, the 120 V input of which is transformed to a 240 V output. The primary coil has 18 loops and draws a current of 0.200 A when in use. [br][br]What is the number of loops in the secondary coil?
What is the current output of the secondary coil?