- #1

Boris_The_Red

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## Homework Statement

A 40 turn circular coil of a 4.0 cm radius and a total resistance of 0.20 Ω is placed in a uniform magnetic field directed perpendicular to the plane of the coil. The magnitude of the magnetic field varies with time as B = 50*sin(10π*t)

**mT**where t is measured in s. What is the induced current in the coil at 0.10 s?

## Homework Equations

I believe these are the equations needed:

**ε = -N*d(Φ**

I = V/R

Φ

_{B})/dtI = V/R

Φ

_{B}= ∫B*dA## The Attempt at a Solution

The way I did it was start off with

**I = V/R**, then knowing that V is the emf, I plugged in

**ε = -N*d(Φ**

_{B})/dt.Then I used the flux equation, but modified it since we were given dB (or what I assume is dB) and I thus get

**I = (-N* ∫dB*A)/ R.**

From there I get

**I = (-N*50*sin(10π*t)*10**

^{-3}*πr^{2})/RI solve this, but I don't get the correct answer (which is known since this is from an older exam that I'm doing as additional practice for my fnal).

Am I missing something key here, or did I improperly set up the mag. field equation?