# Induced emf/current

1. Feb 22, 2009

### themoleculoma

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

Resistance = R
Angle = theta
B = 2cos(2t)
Circular wire loop where magnetic field acts at theta degrees with respect to the normal of the wire loop.

Find induced current and emf in wire loop. Find induced electric field at radial distance d from center of wire loop.

2. Relevant equations

$$\epsilon$$ = -d$$\Phi$$/dt
I = $$\epsilon$$/R

3. The attempt at a solution

A = $$\pi$$r$$^{}2$$
$$\epsilon$$ = d(BA)/dt
= A dB/dt
= $$\pi$$r$$^{}2$$ d(2cos(2t))/dt
= -4$$\pi$$r$$^{}2$$ sin(2t) = induced emf (area not changing)

Given a magnetic field B with a constraint of 2t for $$\omega$$t, and no time, the answer must be with respect to t, correct? You can't use the frequency given by 2/2pi can you?

i = $$\epsilon$$ / R
i = -4$$\pi$$r$$^{}2$$ sin(2t) / R

Since I still don't know time I'm guessing I have to solve as a function of t?

$$\epsilon$$ = dB/dt d/2 = -2sin(2t)d

Last edited: Feb 22, 2009