- #1

Angie K.

- 108

- 1

## Homework Statement

A 34.6 -cm-diameter coil consists of 25 turns of circular copper wire 2.25 mm in diameter. A uniform magnetic field, perpendicular to the plane of the coil, changes at a rate of 3.55 × 10-3T/s. Determine

a. the current

*I*in the loop,

b. and the rate

*dU*/

*dt*at which thermal energy is produced.

## Homework Equations

magnetic flux = B*A cos Theta

I = magnetic flux / R

R = p (L/A) where p is the resistivity of copper

## The Attempt at a Solution

Here is what I attempted:

First, I found the magnetic flux by using the formula: B*A cos Theta

multiplying the area by 25 because it's in a coil and using .173 meters for the radius of the coil

(3.55*10^-3)(25*.173) = 1.535375*10^-2

then to find I (current) :

I = magnetic flux / resistance

I calculated resistance by :

since it's a coil, I multiplied the L by 25 and the A by 25

R = p (L/A) = 1.68*10^-8 (25*pi*.173 / 25*pi*1.125*10^-2)^2 = 0.001148

plugging in that into the I equation, I = 1.535375e-2 / 0.001148 = 13.374 A

This isn't the right answer and I messed something up. I would appreciate if someone could help me with catching my mistake! I appreciate it!

Thanks in advance!