Part 1
3. An electron follows a helical path in a uniform magnetic field of magnitude 0.422T. The pitch of the path is 6.81 ?m, and the magnitude force on the electron is 1.59 x 10-15 N. What is the electron's speed?
4. A cyclotron with dee radius 45.9 cm is operated at an oscillator frequency of 12.9 MHz to accelerate protons. (a) What magnitude B of magnetic field is required to achieve resonance? (b) At that field magnitude, what is the kinetic energy of a proton emerging from the cyclotron? Suppose, instead, that B= 1.49T. (c) What oscillator frequency is required to achieve resonance now? (d) At that frequency, what is the kinetic energy of and emerging proton?
5. A horizontal power line carries a current of 6110 A from south to north. Earth's magnetic field (86.8 ?T) is directed toward the north and is inclined downward at 70 degrees to the horizontal. Find the magnitude of the magnetic force on 100m of the line due to Earth's field.
7. A surveyor is using a magnetic compass 7.1 m below a power line in which there is a steady current of 120A. What is the magnetic field in microteslas at the site of the compass due to the power line?
11. In a particular region there is a uniform current density of 18 A/m2 in the positive direction. What is the value of ?B•ds when that line integral is calculated along the three straight-line segments from (x, y, z) coordinates (5d, 0, 0) to (5d, 3d, 0) to (0, 0, 0) to (5d, 0, 0), where d = 19 cm?
14. A toroid having a square cross-section, 5.48cm on the side, and an inner radius of 19.4cm 450 turns and carries a current of 1.04A. (It is made up of a square solenoid instead of round one bent into doughnut shape.) What is the magnitude field inside the toroid at (a) the inner radius and (b) the outer radius?
15. A 240-turn solenoid having a length of 21 cm and a diameter of 8.8 cm carries a current of 0.44A. Calculate the magnitude of the magnetic field inside the solenoid.
Part 2
7. A long solenoid has a diameter of 10.4cm. When a current I exists in its windings, a uniform magnetic field of magnitude B=37.7 mT is produced in its interior. By decreasing I, the field is causes to decrease at the rate of 7.23 mT/s. Calculate the magnitude of the induced field (a) 3.75cm and (b) 8.58cm from the axis of the solenoid.
9. A circular coil has a 12.8cm radius and consists of 29.0 closely wound turns of wire. An externally produced magnetic field of magnitude 2.23 mT is perpendicular
to the coil. (a) if no current is in the coil, what magnetic flux links its turn? (b) When the current in the coil is 5.47A in a certain direction, the net flux through the coil is found to vanish. What is in henrys the inductance of the coil?
11. The current in an RL circuit builds up one-third of its steady value in 4.56s. Find the inductive time constant.
12. The current is an RL circuit drops from 1.1 A to 13 mA in the first second following removal of the battery from the circuit. If L is 12H, find the resistance R in the circuit.