Your employer asks you to build a 26-cm-long solenoid with an interior field of 6.0 mt . the specifications call for a single layer of wire, wound with the coils as close together as possible. you have two spools of wire available. wire with a #18 gauge has a diameter of 1.02 mm and has a maximum current rating of 6 a. wire with a #26 gauge is 0.41 mm in diameter and can carry up to 1 a. which wire should you use, and what current will you need?

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.