## anonymous one year ago A straight 1.2 m length iron rod is moved at 10 m/s through the earth's magnetic field at a location where it has magnitude 1.0 × 10^-5 T. What is the magnitude of the induced emf between one end of the wire and the other end? A. 1.2 V B. 1.2 × 10^-4 V C. 1.0 × 10^-4 V D. 120 V

1. Michele_Laino

I'm pondering...

2. anonymous

ok!

3. Michele_Laino

during the motion of that iron rod, an electric field will appear inside that iron rod, since all free electrons inside that rod are underwent to the Lorentz force. Now the motion of such free electrons will terminate when the Lorentz force is balanced with the resultant electrostatic force. The situation is as below: |dw:1434343667110:dw|

4. anonymous

yes:)

5. Michele_Laino

so we can write: $\Large evB = e\frac{V}{L}$ where V is the emf force, and v is the velocity of the iron rod after a simplification we get: $\Large V = vBL$

6. Michele_Laino

L is the length of the iron rod

7. anonymous

ok! what do we plug in?

8. Michele_Laino

here is the next step: $\Large V = vBL = 10 \times {10^{ - 5}} \times 1.2 = ...volts$

9. anonymous

ok! we get 1.2E-4? so choice B is our solution? :O

10. Michele_Laino

that's right!

11. anonymous

ooh yay! thanks:)

12. Michele_Laino

:)

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