You hold your hand 3 feet above the ground and look at the shadow cast by the sun. You repeat this inside using the light from a 2 foot by 4 foot fluorescent light box in the ceiling. In which case will the penumbra be more pronounced? Which of these two sources is acting more like a point source?

ill do it for 100, also this isnt 80 its 40

we need to know the time interval during which the force acts. impulse of force = momentum change

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.