# Homework Help: Faraday's and Len's Law

1. May 13, 2015

### skarner

1. The problem statement, all variables and given/known data
You are looking down at a flat coil of 200 turns of wire. It encloses an area of 10.0 cm by 10.0 cm. This coil is immersed in a uniform magnetic field of 0.500 T that penetrates the entire area. The field is pointing up towards you, the observer. The field is then shut off so that it drops to zero in 200.0 ms. The resistance in the coil of wire is 25.0 .

a) What is the average induced emf?
b) In what direction is the induced magnetic field?
c) What is the direction of the induced current?
d) What is the magnitude of the induced current?
e) What power has been generated in this circuit?

2. Relevant equations
o = B(A)Cos
s= - N(o)/t
I = V/R
P = VI

3. The attempt at a solution
a) o =(0.500T)(0.01m^2)(Cos 0o)
o = 0.005 Wb
s = - (200)(0.005Wb)/(0.2s)
= -5.00v

b) Induced magnetic filed is pointing towards me.

c) Anticlockwise

d) I = 5.00V/25.0(ohm)
= 0.20 A

e) P = (0.20A)(5.00V) = 1.00 W

2. May 13, 2015

### skarner

This is first time trying out here, so I hope I didn't miss anything.

Last edited: May 13, 2015