A counterclockwise current I is induced in the loop. The magnetic force FR on the bar carrying this current opposes the motion. Figure 30.8 (a) A conducting bar sliding with a velocity v along two conducting rails under the action of an applied force F Because of the current in the bar, there is a magnetic force F,on the bar in the direction opposite to the applied force. (b) The equivalent circuit diagram for the setup shown in (a). R F, app R |El = Blv app a I * * x x x B,n a 'in R Figure P30.18

Still think that unit conversion isn't important? Here is a widely publicized, true story about how failing to convert units resulted in a huge loss. In 1998, the Mars Climate Orbiter probe crashed into the surface of Mars, instead of entering orbit. The resulting inguiry revealed that NASA navigators had been making minor course corrections in SI units, whereas the software written by the probe's makers implicitly used British units. In the United States, most scientists use Sl units, whereas most engineers use the British, or Imperial, system of units. (Interestingly, British units are not used in Britain.) For these two groups to be able to communicate to one another, unit conversions are necessary. The unit of force in the SI system is the newton (N), which is defined in terms of basic Sl units as 1 N=1 kg · m/s?. The unit of force in the British system is the pound (lb), which is defined in terms of the slug (British unit of mass), foot (ft), and second (s) as 1 lb =1 slug ·…

Three loops of wire move near a long straight wire carrying a current as in Figure P20.9. What is the direction of the induced current, if any, in (a) loop A, (b) loop B, and (c) loop C. A B I C Figure P20.9

As a diligent physics student, you carry out physics experiments at every opportunity. At this opportunity, you carry a 1.33 m long rod as you jog at 3.25 m/s, holding the rod perpendicular to your direction of motion. What is the magnitude B of the magnetic field that is perpendicular to both the rod and your direction of motion and that induces an EMF of 0.283 mV across the rod? Express the answer in milliteslas. B = mT

A 35.6-meter-long spacecraft flies past a neutron star, and passes through the neutron star s extremely powerful magnetic field of strength 7.95 x 10^4 T. The spacecraft travels at a velocity of 2.43 km/s in a direction perpendicular to the magnetic field; the spacecraft s long axis is also perpendicular to the magnetic field. What is the induced emf (voltage) between the two ends of the spacecraft?     6.88E+08 V     6.88E+09 V     6.88E+06 V     6.88E+05 V

In the figure below, the two ends of a U-shaped wire of mass m = 7.00 g and length L = 17.0 cm are immersed in mercury (which is a conductor). The wire is in a uniform field of magnitude B = 0.0860 T. A switch (unshown) is rapidly closed and then reopened, sending a pulse of current through the wire, which causes the wire to jump upward. If jump height h = 4.00 m, how much charge was in the pulse? Assume that the duration of the pulse is much less than the time of flight. Hg. Number i X L X Units X M