A student rubs a glass rod with a piece of silk to charge it. He then touches it to a metal sphere hung from a string. Which statement correctly describes what
happens?
a) The metal sphere will be attracted to the glass rod after it is touched.
b) The metal sphere will be repelled by the glass rod after it is touched.
c) The metal sphere will have a negative charge after the glass rod touches it.
d) The metal sphere becomes neutral once the glass rod is removed.

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.

What is the magnitude of the acceleration vector which causes a particle to move from velocity −5i−2j m/s to −6i+ 7j m/s in 8 seconds. answer in m/s.

If a substance is in the gas phase, which of qualities of the gas will stay constant? a: volume b: mass c: shape d: position of particles