HELLO CAN SOMEONE PLEASE ANSWER THIS !!! How is a conductor different from an insulator?

1: Conductors do not have magnetic fields; insulators do have magnetic fields.
2: In a conductor, electric current can flow freely; in an insulator, it cannot flow freely.
3: In a conductor, electric current cannot flow freely; in an insulator, it can flow freely.
4: Conductors have magnetic fields; insulators do not have magnetic fields.

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.

Four point charges each having charge q are located at the corners of a square having sides of length a. find symbolic expressions for the following. (a) the total electric potential at the center of the square due to the four charges (use any variable or symbol stated above along with the following as necessary: ke.) vtotal= (b) the work required to bring a fifth charge p from infinity to the center of the square (use any variable or symbol stated above along with the following as necessary: w=

You are doing a science experiment with a fahrenheit thermometer. your data must be in degrees celsius. if you measure a temperature of 125°f, what is this temperature in degrees celsius