Concept explainers
Professor Edward Ney was the founder of infrared astronomy at the University of Minnesota. In his later years, he wore an artificial pacemaker. Always an experimentalist, Ney often held a strong laboratory magnet near his chest to see what effect it had on his pacemaker. Perhaps he was using the magnet to throw switches that control different modes of operation. An admiring student (without an artificial pacemaker) thought it would be fun to imitate this great man by holding a strong magnet to his own chest. The natural pacemaker of the heart (known as the sinoatrial node) carries a current of about 0.5 mA. Estimate the magnetic force exerted on a natural pacemaker by a strong magnet held to the chest. How do you think the student might have felt during the experiment? Explain your geometric assumptions. Hints: See Table 30.1 (page 941) to estimate the magnetic field, and assume the field is roughly uniform. Use Figure P30.58 to estimate the size of the sinoatrial node; your heart is about the size of your fist.
FIGURE P30.58
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Physics for Scientists and Engineers: Foundations and Connections
- An iron (density ρ) rod with length L, cross sectional area A, spans across two parallel, metal train tracks. The tracks are connected to a power supply and have a potential ∆V across them. Between the tracks are placed magnets such that the B-field points directly upwards with strength B. What is the acceleration of the iron rod be the moment it starts from rest? What will acceleration be as a function of speed as it continues? Assume the contact is frictionless between the tracks and the rod so that no force of friction needs to be overcome. What will the top speed of the rod be under these conditions?arrow_forwardFor this question, we have to consider an experimental setup where charged particles (electrons or protons) are first accelerated by an electric field and then injected into a region of constant magnetic field with a field strength of 0.55 T. What is the potential difference, in volts, required to accelerate electrons to a speed of 5.8 * 10^(7) ? Also what is the radius of curvature, in meters, of the path of a proton accelerated through this same potential after the proton crosses into the region with the magnetic field? This is not a graded questionarrow_forward5. Suppose we have a stationary external magnetic field B. We have a negatively charged particle of charge Sql and mass m. Initially, it is moving vertically upwards with speed vol and no horizontal velocity. The particle can move freely in x and y directions. (a) Plot the vertical velocity and vertical position of the particle and provide the corresponding expressions. Consider the origin to be the center of the particle's path. (Two plots, two expressions) Vy y Vy vy(t) = ? y y(t) = ? vy(t) = ? (b) Let the B field be doubled and repeat the plots from (a). How are the plots different from part (a)? (Two plots, one short answer) y(t) = ? B t X Vo -|8q|, marrow_forward
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- Physics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning