On a typical clear day, the atmospheric electric field points downward and has a magnitude of approximately 119 N/C. Compare the gravitational and electric forces on a small dust particle of mass 3.3 ✕ 10−15 g that carries a single electron 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?