Which of the following statements describes the interaction between magnetic poles? a. like poles attract each other. b. like poles repel each other, and opposite poles attract each other. c. opposite poles repel each other. d. like poles attract each other, and opposite poles repel each other.

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.

Acompound machine is also called a machine. a. force b. simple c. complex d. directional

Give an example in which the electrical energy changes to light energy