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edugen Wiley plus.com Wiley PLUS question I Chegg.com Return to Blackboard Wiley PLUS Cutnel Physics, 10e Help I System Announcements Assig Assignment Open Assignment PRINTER VERSION BACK NEXT ASSIGNMENT RESOURCES Chapter 22, Problem 01. A 0.80-m aluminum bar is held with its length parallel to the east-west direction and dropped from a bridge. Just before the bar hits the river below, its speed is 24 m/s, and the emf induced across its length is 7.8 x 10 4 V. Assuming the horizontal component of the Earth's magnetic field at the location of the bar points directly north, (a) determine the magnitude of the horizontal component of the Earth's magnetic field, and (b) state whether the east end or the west end of the bar is positive, 04 22, Prob Chapter 22 Problem o4 a) Number Units Chapter 22 Problem 12 Chapter 22 Problem the tolerance is +/-6% Chapter 22 Problem 21 Chapter 22, Problem 33 Chapter 22, Probl Chapter 22 Probl Chapter 22 Problem 41 Chapter 22 Probl By accessing this Question Assistance, you will learn while you earn points based on the Point Potential Policy set by your instructor, Stu Question Attempts: Unlimited SAVE FOR LATER SUBMIT ANSWER Objective Eam Maximum Points available only if you answer this question correctly in four attempts or less. Copyright O 2000-2017 by John Wiley & Sons, Inc. or related companies. All rights reserved License Agreement Privacy Policy l 2000-2012 2ohn Wiley Sons Inc. All Rights Reserved. A Division o lohn Wiley & Sons inca Version 4.22.2.9

Explanation / Answer

This is called motional EMF.

In simplest terms, if velocity v, length L and magnetic field B are mutually perpendicular, EMF = vLB.

Since EMF is not a vector we can't refer to its direction, but we can determine the direction of the induced E field. From E = v x B, where x is the vector cross product.

Then EMF = ELcos(theta) where theta is the angle between E and L (i.e., EMF = E dot L). (Note that L is bidirectional, so we can keep theta between 0 and 90 deg.)
a) Here we use the scalar equation since only the horizontal component is asked for.
B(hor) = EMF/(vL) = 4.0625E-5 T

b) Here we only need to know whether E has an east or a west component, so we use the right-hand rule with

E = v x B. Since v points down and B has a north component, E has an east component.

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