Final answer:
The student's question revolves around calculating electric fields produced by charged wires and understanding the right-hand rule for magnetic fields created by current-carrying wires. Methods involve Coulomb’s law, principle of superposition, and Ampere's law
Step-by-step explanation:
The questions posed relate to the concept of electric fields produced by charges distributed on wires and plates, and involve using principles of electromagnetism to find these fields. Furthermore, the direction of magnetic fields around current-carrying wires can be determined by the right-hand rule.
Finding the Electric Field above the Midpoint of a Charged Wire
To solve the first part, one would calculate the electric field produced by a straight, uniformly charged wire at a point in space using Coulomb’s law and the principle of superposition. The electric field would be computed by integrating contributions from each infinitesimal piece of the wire. The direction of the electric field would be radially away from the wire if the charge is positive, and toward the wire if the charge is negative.
Finding the Electric Field Above the Center of a Circularly Bent Wire
For a wire bent into a circle, the process is similar, but the symmetry of the problem simplifies it. Since at the point above the center all the parts of the wire contribute equally but in different directions, if the wire is uniformly charged, the vertical components of the electric fields from opposite elements of the wire cancel out, leaving no net electric field at the center of the circle above the wire.
Using the Right-Hand Rule to Determine the Direction of a Magnetic Field
When it comes to magnetic fields produced by current-carrying wires, as described by Ampere's law, one can use the right-hand rule to determine the direction of the magnetic field. If the wire carries current, your right thumb points in the direction of the current, and the fingers curl in the direction of the magnetic field that wraps around the wire in concentric circles.