A transformer is used to operate a model train. The transformer, which is plugged into a standard electrical outlet, produces an output voltage of 15.0 V (rms), applied to the train's tracks. (The voltage supplied to transformer from outlet is 120 V.) (a) What is the ratio of the number of turns in the primary to the number of turns in the secondary?
(b) If the train uses an average power of 14.0 W, what are the rms currents in the secondary and in the primary? Assume an ideal transformer, with no energy loss.

The functioning of an electron transport chain is analogous to a) a slinky toy going down a flight of stairs. b) a canoe going over a waterfall. c) a person climbing a flight of stairs one step at a time. d) a person leaping from the top to the bottom of a flight of stairs in one jump.

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

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.