C.7 Can the force from a steady magnetic field cause the speed of a moving charged particle to change? Explain.Yes No
C.8 Is your electric blanket safe? It has been theorized that excess nighttime exposure to electromagnetic fields may reduce the
production of the hormone melatonin in certain women. Furthermore, reduced melatonin levels might lead to an increased risk
of breast cancer. Scott Davis at Seattle's University of Washington School of Public Health and Community Medicine was one
of the first to investigate links between electromagnetic fields and cancer (particularly leukemia). He has been quoted as
saying, "Electric blankets were pretty effectively re-engineered a number of years ago. Modern-day electric blankets í
anything you buy in the store now í (has a different) configuration of the heating elements in the blanket so that it doesn't
produce any magnetic fields." How could the wiring in an electric blanket be designed to minimize or eliminate the production
of external magnetic fields?C.9 Can the force from a steady magnetic field cause a stationary charged particle to start moving? Explain.
Yes No
C.10An up-and-coming entrepreneur, long on marketing skills but short on physics knowledge, develops a "new and improved"
device for detecting current-carrying wires inside household walls. This is something a do-it-yourselfer really needs to know
before picking up the old saber-saw and starting to cut out that new doorway! The "Mag-Flag Juicefinder," which costs
$79.99, is actually nothing but a magnetized needle free to rotate. The advertising materials explain that the wires in the walls
generate magnetic fields, and that the needle will align with these fields in a direction perpendicular to the hidden wires. Why
will this device not work? Hint: Household wiring cables inside the walls contain three wires bundled close together. One is a
"ground," and the same amount of current flows in opposite directions through the other two.C.11Each of the diagrams (a), (b), (c), and (d)
represents a positively charged particle
moving at velocity v through a magnetic field
B whose field lines are shown. In each case,
tell the direction of the force experienced by
the moving particle in the field.
(a) i. Right
ii. Left
iii. Up
iv. Down
v. Toward you
vi. Away from you
(b) i. Right
ii. Left
iii. Up
iv. Down
v. Toward you
vi. Away from you
(c) i. Right
ii. Left
iii. Up
iv. Down
v. Toward you
vi. Away from you
(d) i. Right
ii. Left
iii. Up
iv. Down
v. Toward you
vi. Away from you(^528) Copyright 2007 Kinetic Books Co. Chapter 28 Problems