You are Here: Home >< Physics

# Trasnformers watch

1. (Original post by Mehh)
Okay...
Vout = - n2dΦ/dt
Iin n1 = Φ

That all that is known for sure. The phase of Vin relative to Iin is dependant on the coil and the power supply. The phase of Vout relative to Iout is dependant on the secondary coil and the load(s). However for the most parts, I don't believe you need to know this for ALevel Physics. If you did need to know you would probabily know a wee bit about complex impediance [Z = V/I].
so current and flux are in the same phase? And current and flux have a phase difference of pi/2 against voltage?
2. As the formula for the magnetic field strength inside the solenoid (2 coils in the transformer are considered as 2 solenoids) B = µ.n.I
And magnetic flux , Φ = NBA = µ.n.N.A.I
So the flux should be in-phase with the current.
Whereas, e.m.f, E = -dΦ/dt = -k.dI/dt (k>0)
If I = Io.sin2πft -> dI/dt = Io.cos2πft = Io.sin(2πft + π/2)
So it's obviously, the induced e.m.f is different π/2 relative to the current.

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 15, 2005
The home of Results and Clearing

### 1,012

people online now

### 1,567,000

students helped last year
Today on TSR

### University open days

1. Keele University
Sun, 19 Aug '18
2. University of Melbourne
Sun, 19 Aug '18
3. Sheffield Hallam University