Two power lines, line 1 and line 2, both of length ll = 56 m, are strung east-west between two towers. line 1 is r12 = 2.4 m directly above line 2. the current in both power lines is il = 75 a to the west. assume the power lines are straight and you can use the approximation r12 < < ll. a) find the magnitude of the magnetic field b21, in teslas, produced by line 1 at line 2.b) calculate the magnitude of the magnetic force f21, in newtons, that the current in line 1 exerts on line 2.c) assume a typical power line has a mass of 890 kg per 1000 m. how many times larger would the current in both lines have to be for the magnetic force on the line to balance the force of gravity?

Does work output exceed work input when a machine is used? a) yes, it does, as machines create energy. b) it depends on the type of machine used. c) no, it doesn’t, as machines are inefficient. d) no, it doesn’t, as machines cannot create energy.

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.

You are given two vectors a⃗ =−3.00ι^ 5.00j^ and b⃗ =5.00ι^ 2.00j^. let the counterclockwise angles be positive.