For what visible wavelengths of light do the reflected waves interfere constructively? the range of wavelength of visible light is from 380 nm to 750 nm.

None of the wavelength is in the visible range

Explanation:

Constructive interference of the reflected waves for different wavelengths can be estimated using:

λ = 2nd/m

where m is 1,2,3, ...

Therefore:

m=1, λ = 750 nm

m=2, λ = 750/2 = 375 nm

The limits of eye's sensitivity is between 430 nm and 690 nm. Beyond this range, the eye's sensitivity drops to approximately 1% of its maximum value.

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it

you'd use the equation that establishes a relationship between  energy  and  wavelength, which looks like this

e=h⋅cλ, where

λ  - the wavelength of the photon; c  - the speed of light, usually given as  3⋅108m/s; h  -  planck's constant, equal to  6.626⋅10−34j s

plug the value you were given for the energy of the photon in the above equation to get the wavelength

e=h⋅cλ⇒λ=h⋅ce

λ=6.626⋅10−34js⋅3⋅108ms−1.257⋅10−24j=1.581⋅10−1m