Question

PART A

Two light waves of the same frequency start out in phase (with amplitudes going up at the same moment), and they interfere having traveled different distances.  What happens if the path difference in the two waves is 1200 nm and the wavelength of the light is 400 nm (blue light)?

		The waves add in step and the  time-averaged power at that place is 4x that of one wave alone.
		The waves add in step and the  time-averaged power at that is 2x that of one wave alone.
		The waves add in step and the  time-averaged power is that of one wave alone.
		The waves cancel and there is no power at this place.

PART B

Energy carried by light. Pick ALL those that apply

		is proportional to both electric and magnetic fields
		is proportional to the square of the electric field
		is proportional to the amplitude of the electric field
		flows perpendicular to both the electric and the magnetic fields
		flows in the direction of the electric field

PART C

Suppose you are experimenting with a Michelson interferometer and you have adjusted it so that you see a pattern of circular rings of interference. You illuminate the interferometer with light from sodium atoms which emit two wavelengths, 589 and 596 nm. What do you see?  Pick ALL that apply.

		The difference is so small that the rings from both wavelengths always lie on top of one another.
		For the same order of interference, the rings from the longer wavelength light fall inside the rings of the shorter wavelength light.
		For some spacings of mirrors, the rings from the two lines may fall exactly between one another.
		You could adjust a mirror to make the rings of the two wavelengths lie on top of one another, and then change it to make them lie between one another.
		There are no rings visible because there are two wavelengths present.

Answer 1

Part A) The waves add in step and the  time-averaged power at that place is 4x that of one wave alone. It is so because the path difference is an integral multiple of the wavelength, thus the interference is constructive.

Part B) is proportional to the square of the electric field; is proportional to both electric and magnetic fields; flows perpendicular to both the electric and the magnetic fields

Part C) You could adjust a mirror to make the rings of the two wavelengths lie on top of one another, and then change it to make them lie between one another; For some spacings of mirrors, the rings from the two lines may fall exactly between one another; For the same order of interference, the rings from the longer wavelength light fall inside the rings of the shorter wavelength light.

Please upvote if my answer helped you. Have a nice day.