Two point charges q 4.0 nC and q 6.0 nC are located on the x axis at x 3.0 cm and x 3.0 cm respectively a Find a position or positions on the x axis other than infinity where the electric potential is zero 2 b How much work is needed to bring a third charge q 2.0 nC from infinity to the point x 0 in the above set up 2 c When you have the third charge q 2.0 nC at the point x 0 and the other charges where they are what is the electric potential energy of the whole system of the three charges 3

Use the table to answer question 22 23 and 24.

Some material consisting of a collection of microscopic objects is kept at a high temperature. a photon detector capable of detecting photon energies from infrared through ultraviolet observes photons emitted with energies of 0.3 ev, 0.5 ev, 0.8 ev, 2.0ev, 2.5ev, and 2.8ev. these are the only photon energies observed. (a) draw and label a possible energy-level diagram for one of the microscopic objects, which has four bound states. on the diagram, indicate the transitions corresponding to the emitted photons. explain briefly. (b) would a spring–mass model be a good model for these microscopic objects? why or why not? (c) the material is now cooled down to a very low temperature, and the photon detector stops detecting photon emissions. next, a beam of light with a continuous range of energies from infrared through ultraviolet shines on the material, and the photon detector observes the beam of light after it passes through the material. what photon energies in this beam of light are observed to be significantly reduced in intensity (“dark absorption lines”)? explain briefly.

Which notation is used to represent an alpha particle? a. b. c. d.