Physics Electrodynamics

| Two small spheres, each with mass m = 3.0 g and charge q, are suspended from a point by threads of length L = 0.22 m. What is the charge on each sphere if the threads make an angle  = 15º with the vertical? | | A) 0.79 C B) 2.9 C C) 75 mC D) 6.3 C E) 0.11 C | | | | Three charges, each of Q = 3.2  10–19 C, are arranged at three of the corners of a 20-nm square as shown. The magnitude of the electric field at D, the fourth corner of the square, is approximately | A) | 1.4  107 N/C | D) | 30 N/C | B) | 1.0  1011 N/C | E) | 1.8  107 N/C | C) | 3.6  1010 N/C | | | | | | An infinitely long cylinder of radius 4.0 cm carries a uniform volume charge density  = 200 nC/m3. What …show more content…

The loop is oriented as shown in a uniform magnetic field of 1.5 T. The force acting on the upper 0.10-m side of the loop is | | A) 1.5 N B) 0.75 N C) 0.50 N D) 0.15 N E) zero | | |

| A beam of electrons (q = 1.6  10–19 C) is moving through a region of space in which there is an electric field of intensity 3.4  104 V/m and a magnetic field of 2.0  10–3 T. The electric and magnetic fields are so oriented that the beam of electrons is not deflected. The velocity of the electrons is approximately | A) | 6.8  106 m/s | D) | 0.68 km/s | B) | 3.0  108 m/s | E) | 1.7  107 m/s | C) | 6.0  10–9 m/s | | | | | | A doubly ionized oxygen atom 16O2+ is moving in the same uniform magnetic field as an alpha particle. The velocities of both particles are at right angles to the magnetic field. The paths of the particles have the same radius of curvature. The ratio of the energy of the alpha particle to that of the 16O2+ ion is | A) | E /EO = 1/1 | D) | E /EO = 4/1 | B) | E /EO = 1/4 | E) | None of these is correct. | C) | E /EO = 1/16 | | | | | Use the diagram for the next three problems.Electrons traveling at a speed of v0 = 3  107 m/s pass through the deflection plates. The electric field between the plates is E = 5000 V/m and spans a distance of x1 = 5 cm. The electrons then travel a further distance