# Calculate the EMF induced in the square?

Tags:
1. Mar 30, 2016

### hrf2

1. The problem statement, all variables and given/known data

1. A square of wire with side length 1.4 m rotates about an axis through one corner that is perpendicular to the plane of the square with an angular speed of 3 rev/s. There is a uniform magnetic field of 1.2 T perpendicular to the square. Calculate the EMF induced in the square.

2. Relevant equations
I know we'll need E=N*B*A*w; here, N=1, B=1.2T, and I thought A=1.96 m2, but I'm not sure now.

3. The attempt at a solution
I attempted to do the equation at face-value but realized my geometry is not correct. How would you set up this problem geometrically? I think the problem should be set up with a square formed by the x and z axis and the axis of rotation at the y, maybe something like the diagram I uploaded. But then how do I form the equation from there?

Thanks for any help in advance!

#### Attached Files:

• ###### diagram.png
File size:
1.1 KB
Views:
55
2. Mar 31, 2016

### Hesch

The flux, ψ = B * A.

E = dψn / dt = dψ / dt , ( N = 1 ).

So calculate the amount of flux, dψ, that the square crosses within a time, dt.

3. Apr 1, 2016

### rude man

How does the B field, and therefore the flux, vary with time as the square rotates around the wire? Your answer will be a function of time (unless you express the emf as rms or peak volts).