Students in a lab are doing experiments involving the motion of objects. They pull an object across a table and use a detector to measure the acceleration of the object for the entire time they pull it. The graph shows the data from
the detector, with four segments labeled.
Acceleration
3
Time
For which segments of the motion is there a net force on the object? Explain how the graph indicates this. Enter
your answer in the box provided.

Suppose that an electromagnetic wave which is linearly polarized along the x−axis is propagating in vacuum along the z−axis. the wave is incident on a conductor which is placed at z > 0 region of the space. the conductor has conductivity σ, magnetic permeability µ and electric permittivity ε. (a) find the characteristic time for the free charge density which dissipates at the conductor. (b) write the maxwell equations and derive the wave equation for a plane wave propagating in a conductor. (c) find the attenuation distance at which the incident amplitude reduces to e ^−1 of its initial value. (d) find the electric and magnetic fields inside the conductor. 8 (e) find the power loss per area of the incident electromagnetic wave at the surface of conductor.