An MRI technician moves his hand from a region of very low magnetic field strength into an MRI scanner’s 2.00T field with his fingers pointing in the direction of the field. Find the average emf, in millivolts, induced in his wedding ring given its diameter is 2.36cm, and assuming it takes 0.462s to move it into the field.

An MRI technician moves his hand from a region of very low magnetic field strength into an MRI scanner’s 2.00T field with his fingers pointing in the direction of the field. Find the average emf, in millivolts, induced in his wedding ring given its diameter is 2.36cm, and assuming it takes 0.462s to move it into the field.

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter12: Sources Of Magnetic Fields

Section: Chapter Questions

Problem 12.7CYU: 12.7 Check Your Understanding What is the ratio of the magnetic field produced from using a finite...

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A flat, square coil of 20 turns that has sides of length 15.0 cm is rotating in a magnetic field of strength 0.050 T. If tlie maximum emf produced in die coil is 30.0 mV, what is the angular velocity of the coil?
A parallel-plate capacitor with plate separation d is connected to a source of emf that places a time-dependent voltage V(t) across its circular plates of radius r0and area (a) Write an expression for the time rate of change of energy inside the capacitor in terms of V(t) and dV(t)/ dt. (b) Assuming that V(t) is increasing with time, identify the directions of the elecuic field lines inside the capacitor and of the magnetic field lines at the edge of the region between the plates, and then the direction of the Poynting vector S at this location. (c) Obtain expressions for the time dependence of E(t), for B(t) from the displacement current, and for the magnitude of the Poynting vector at the edge of the region between the plates. (d) From S , obtain an expression In terms of ‘(t) and dV(t)/dt for the rate at which electromagnetic field energy the region between the plates. (e) Compare the results of pails (a) and (d) and explain the relationship between them.
An automobile with a radio antenna 1.0 m long travels at 100.0 km/h in a location where theEarth’s horizontal magnetic field is 5.5105T . What is the maximum possible emf induced in the antenna due to this motion?
A thin conducting bar (60.0 cm long) aligned in the positive y direction is moving with velocity v=(1.25m/s)i in a region with a spatially uniform 0.400-T magnetic field directed at an angle of 36.0 above the xy plane. a. What is the magnitude of the emf induced along the length of the moving bar? b. Which end of the bar is positively charged?
A single-turn circular loop of wire of radius 50 mm lies in a plane perpendicular to a spatially uniform magnetic field. During a 0.10-s time interval, the magnitude of the field Increases uniformly from 200 to 300 mT. (a) Determine the emf Induced in the ioop. (b) If the magnetic field is directed out of the page, what is the direction of the cun-ent induced in the loop?
The accompanying figure shows a metal disk of inner radius r1 and other radius r2 rotating at an angular velocity while in a uniform magnetic field directed parallel to the rotational axis. The brush leads of voltmeter are connected to the dark's inner and outer surfaces as shown. What is the reading of the voltmeter ?
A square loop whose sides are 6.0-cm long is made with copper wire of radius 1.0 mm. If a magnetic field perpendicular to the loop is changing at a rate of 5.0 mT/s, what is the current in the loop?
The square armature coil of an alternating current generator has 200 turns and is 20.0 cm on side. When it rotates at 3600 rpm, its peak output voltage is 120 V. (a) Wliat is the frequency' of the output voltage? (b) What is the strength of the magnetic field in which the coil is turning?
Design a current loop that, when rotated in a uniform magnetic field of strength 0.10 T, will produce an emf =0 sin t. where 0=110V and 0=110V .
Using an electromagnetic flowmeter (Fig. P19.69), a heart surgeon monitors the flow rate of blood through an artery. Electrodes A and B make contact with the outer surface of the blood vessel, which has interior diameter 3.00 mm. (a) For a magnetic field magnitude of 0.040 0 T, a potential difference of 160 V appears between the electrodes. Calculate the speed of the blood. (b) Verify that electrode A is positive, as shown. Does the sign of the emf depend on whether the mobile ions in the blood are predominantly positively or negatively charged? Explain. Figure P19.69
A time-dependent uniform magnetic field of magnitude B(t) is confined in a cylindrical region of radius R. A conducting rod of length 2D is placed in the region, as shown below. Show that the emf between the ends of the rod is given by dBdtDR2D2 . ( Hint: To find the between the ends, we need to integrate the electric field from one end to the other. To find the electric field, use Faraday’s law as “Ampere’s law for E”.)
Check Your Understanding Repeat the previous problem with the magnetic field in the x-direction rather than in the z-direction. Check your answers with RHR-1.