- 8

- 0

**[SOLVED] Average Current Through A Coil Over An Interval**

**1. Homework Statement**

The problem comes from a homework assignment I have. It has to deal with average current flowing through a wire over an interval. It is stated as follows:

A five-turn circular coil of radius 15cm is oriented with its plane perpendicular to a uniform magnetic field of 0.15T. During a 3s time interval, this field increases to 0.2T. If the resistance of the coil is 8[tex]\Omega[/tex], find the average current that flows in the coil during this interval.

**2. Homework Equations**

I know that to find EMF in a setting like this:

E = NAB [The rest doesn't matter since it is perpendicular]

V = iR [Ohm's Law]

**3. The Attempt at a Solution**

Let E1 be before the change, and E2 at the end.

E = NAB

E1 = (5 Turns)(pi*(0.15m)^2)(0.15T) = .0530V

E2 = (5 Turns)(pi*(0.15m)^2)(0.2T) = .0707V

Using these numbers, V = iR and the known resistance, the currents are as follows:

I1 = (.0530V)/(8Ohm) = 0.006625A

I2 = (.0707V)/(8Ohm) = 0.008837A

The average between them over 3 secs, is I1+I2/3s or:

(0.006625A+0.008837A)/3s = 0.005154A

Is my methodology correct? For some reason I feel I may be doing this incorrectly. Any help would be much appreciated.