Answer:
4000 turns
Step-by-step explanation:
The formula to apply is ;
Voltage in secondary coil/ Voltage in primary coil = Turns on secondary coil/Turns in primary coil
Vs/Vp =Ns/Np
Given that;
Ns=200
Vp=380 V
Vs=19 V
Applying the formula as;
Vs/Vp = Ns/Np
19/380 = 200/Np
1/20 =200/Np
Np = 200/0.05
Np= 4000 turns