Apoint charge with charge q1 = 3.10 μc is held stationary at the origin. a second point charge with charge q2 = -4.50 μc moves from the point ( 0.140 m , 0) to the point ( 0.265 m , 0.265 m ). how much work w is done by the electric force on the moving point charge?

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?