A telescope can be used to enlarge the diameter of a laser beam and limit diffraction spreading. The laser beam is sent through the telescope in opposite the normal direction and can then be projected onto a satellite or the Moon. (a)
If this is done with the Mount Wilson telescope, producing a 2.53 m diameter beam of 636 nm light, what is the minimum angular spread of the beam in radians?
rad
(b)
Neglecting atmospheric effects, what is the diameter in meters of the spot this beam would make on the Moon, assuming a lunar distance of 3.84 ✕ 108 m?
m

the force required to move the cart is divided by three or 33.33 n.

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.