Exam 19: Magnetism

After landing on an unexplored Klingon planet, Spock tests for the direction of the magnetic field by firing a beam of electrons in various directions and by observing the following: Electrons moving upward feel a magnetic force in the NW direction; Electrons moving horizontally North are pushed down; Electrons moving horizontally South-East are pushed upward. He naturally concludes that the magnetic field at this landing site is in which direction?

Consider electrons flowing Southward along a horizontal power line. The magnetic field generated directly below the wire by the current is pointing

Two long parallel wires carry currents of 10. A in opposite directions. They are separated by 40. cm. What is the magnetic field in the plane of the wires at a point that is 20. cm from one wire and 60. cm from the other?

What fundamental fact underlies the operation of essentially all electric motors?

A doubly charged ion with velocity 6.0 × 10⁶ m/s moves in a path of radius 30. cm in a magnetic field of 0.80 T in a mass spectrometer. What is the mass of this ion?

Breaking a bar magnet in half will produce

A charged particle is observed traveling in a circular path in a uniform magnetic field. If the particle had been traveling twice as fast, the radius of the circular path would be

The Earth cannot contain a giant permanent magnet because

What happens to the cyclotron frequency of a charged particle if its speed doubles?

Ten meters away from a long straight wire, the field is 10^-4 Tesla. What current flows through the wire?

A wire lying in the plane of the page carries a current toward the bottom of the page, as shown. What is the direction of the magnetic force it produces on an electron that is moving perpendicularly toward the wire, also in the plane of the page, from your right?

Consider two current-carrying circular loops. Both are made from one strand of wire and both carry the same current, but one has twice the radius of the other. Compared to the magnetic moment of the smaller loop, the magnetic moment of the larger loop is

The source of the earth's magnetic field is thought to be due to the motion of charged particles in the earth's

At double the distance from a long current-carrying wire, the strength of the magnetic field produced by that wire decreases to

At a particular instant, a proton moves Eastward in a uniform magnetic field that is directed straight downward. The magnetic force that acts on it is

Consider two current-carrying circular loops. Both are made from one strand of wire and both carry the same current, but one has twice the radius of the other. Compared to the magnetic field at the center of the smaller loop, the magnetic field at the center of the larger loop is

Consider a 1000. Gauss magnetic field along the z axis and a proton moving with an instantaneous velocity of V= 3 î + 4 k km/s (note its speed is 5. km/s composed of 3. km/s along the x axis and 4. km/s along the z axis) [proton: 1.67 × 10^-27 kg and 1.6 × 10^-19 Coulomb]

The earth's magnetic field at the magnetic equator is approximately

A proton, moving in a uniform magnetic field, moves in a circle perpendicular to the field. If the proton's speed tripled, its time to go around its circular path would be

Two parallel straight wires carry currents in the same direction. The magnetic forces between the wires are such that