Aspy satellite circles the earth at an altitude of 212 km and carries out surveillance with a special high-resolution telescopic camera having a lens diameter of 20 cm. if the angular resolution of this camera is limited by diffraction, estimate the separation of two small objects on the earth's surface that are just resolved in yellow-green light =550 nm). use the small-angle approximation for this problem.

The earth's magnetic field, with a magnetic dipole moment of 8.0×1022am2, is generated by currents within the molten iron of the earth's outer core. suppose we model the core current as a 3000-km-diameter current loop made from a 1000-km-diameter “wire.” the loop diameter is measured from the centers of this very fat wire.to decide whether this is a large or a small current density, compare it to the current density of a 7.0 a current in a 2.0-mm-diameter wire.