Many automatic processes use circuits to accomplish a task. Thermostats, automatic light switches, motors, and home security systems all use circuits. Besides common electronic devices such as stereos, iPods, computers, cell phones, video games, TVs, DVD players, what other things in our world use circuits?

Amichelson interferometer operating at a 600 nm wavelength has a 3.02-cm-long glass cell in one arm. to begin, the air is pumped out of the cell and mirror m2 is adjusted to produce a bright spot at the center of the interference pattern. then a valve is opened and air is slowly admitted into the cell. the index of refraction of air at 1.00 atm pressure is 1.00028.how many bright-dark-bright fringe shifts are observed as the cell fills with air?