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Mick Joseph

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- 1. Open Ended30 seconds1 ptThe magnetic field 10 cm from a wire carrying a 1 A current is 2 μT. What is the field 5 cm from the wire?
- 2. Open Ended30 seconds1 ptA wire carries a current of 23 A . Use the data from (Figure 1) to determine at what approximate distance from the wire the magnetic field strength would equal that of a refrigerator magnet. https://session.masteringphysics.com/problemAsset/1872305/5/table24_1.jpg
- 3. Open Ended30 seconds1 ptThe magnetic field at the center of a 1.0-cm-diameter loop is 2.5 mT What is the current in the loop? A long straight wire carries the same current you found in part a. At what distance from the wire is the magnetic field 2.5 mT ?
- 4. Open Ended30 seconds1 ptFor a particular scientific experiment, it is important to be completely isolated from any magnetic field, including the earth's field. The earth's field is approximately 50 μT, but at any particular location it may be a bit more or less than this. A 1.00-m-diameter current loop with 200 turns of wire is adjusted to carry a current of 0.199 A ; at this current, the coil's field at the center is exactly equal to the earth's field in magnitude but opposite in direction, so that the total field at the center of the coil is zero. What is the strength of the earth's magnetic field at this location?
- 5. Open Ended30 seconds1 ptAlthough the evidence is weak, there has been concern in recent years over possible health effects from the magnetic fields generated by transmission lines. A typical high-voltage transmission line is 20 m off the ground and carries a current of 200 A. Estimate the magnetic field strength on the ground underneath such a line. What percentage of the earth's magnetic field does this represent?(Assume that magnetic field strength at the surface of the earth is 5×10−5T)
- 6. Open Ended30 seconds1 ptAn investigator places a sample 1.0 cm from a wire carrying a large current; the strength of the magnetic field has a particular value at this point. Later, she must move the sample to a 6.0 cm distance, but she would like to keep the field the same. By what factor must she increase the current?
- 7. Open Ended30 seconds1 ptA long wire carrying a 4.5 A current perpendicular to the xy-plane intersects the x-axis at x=−2.0cm. A second, parallel wire carrying a 2.0 A current intersects the x-axis at x=+2.0cm. At what point on the x-axis is the magnetic field zero if the two currents are in the same direction? At what point on the x-axis is the magnetic field zero if the two currents are in opposite directions?
- 8. Open Ended30 seconds1 ptWhat is the magnetic field at the center of the loop in the figure? (Figure 1)
- 9. Open Ended30 seconds1 ptYou have a 2.1 m long copper wire. You want to make an N-turn current loop that generates a 1.3 mT magnetic field at the center when the current is 2.0 A . You must use the entire wire. What will be the diameter of your coil?
- 10. Open Ended30 seconds1 ptIn the Bohr model of the hydrogen atom, the electron moves in a circular orbit of radius 5.3×10−11m with speed 2.2×106m/s. According to this model, what is the magnetic field at the center of a hydrogen atom due to the motion of the electron? Hint: Determine the average current of the orbiting electron.
- 11. Open Ended30 seconds1 ptA particle with a charge of q = -5.90 nC is moving in a uniform magnetic field of B⃗ =( -1.20 T ) k^. The magnetic force on the particle is measured to be F⃗ =( −7.60×10−7 N )j^ Can vy, the y component of velocity be determined? Calculate vx. Can vz, the z component of velocity be determined?
- 12. Open Ended30 seconds1 ptAfter being accelerated to a speed of 1.82×105 m/s , the particle enters a uniform magnetic field of strength 0.800 T and travels in a circle of radius 33.0 cm (determined by observing where it hits the screen as shown in the figure). The results of this experiment allow one to find m/q. Find the ratio m/q for this particle.
- 13. Open Ended30 seconds1 ptThe microwaves in a microwave oven are produced in a special tube called a magnetron. The electrons orbit in a magnetic field of 8.9×10−2 T at a frequency of 2.5 GHz , and as they do so they emit 2.5 GHz electromagnetic waves. If the maximum diameter of the electron orbit before the electron hits the wall of the tube is 2.1 cm , what is the maximum velocity the electrons may have?
- 14. Open Ended30 seconds1 ptA cyclotron is used to produce a beam of high-energy deuterons that then collide with a target to produce radioactive isotopes for a medical procedure. Deuterons are nuclei of deuterium, an isotope of hydrogen, consisting of one neutron and one proton, with total mass 3.34×10−27kg. The deuterons exit the cyclotron with a kinetic energy of 6.10 MeV . What is the speed of the deuterons when they exit? If the magnetic field inside the cyclotron is 1.25 T, what is the diameter of the deuterons' largest orbit, just before they exit? If the beam current is 370 μA how many deuterons strike the target each second?
- 15. Open Ended30 seconds1 ptEarly black-and-white television sets used an electron beam to draw a picture on the screen. The electrons in the beam were accelerated by a voltage of 3.0 kV; the beam was then steered to different points on the screen by coils of wire that produced a magnetic field of up to 0.48 T . What is the speed of electrons in the beam? What acceleration do they experience due to the magnetic field, assuming that it is perpendicular to their path? What is this acceleration in units of g? If the electrons were to complete a full circular orbit, what would be the radius?
- 16. Open Ended30 seconds1 ptThe aurora is caused when electrons and protons, moving in the earth's magnetic field of ≈5.0×10−5T, collide with molecules of the atmosphere and cause them to glow. What is the frequency of the circular orbit for an electron with speed 1.0×106m/s? What is the frequency of the circular orbit for a proton with speed 5.0×104m/s?
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