What the use of physics in our life​

What is special about a dc circuit ?

This is one type of line graph in which the independent variable is time plotted on the x axis and the dependent variable, also numerical, is plotted on the y axis.

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?