In which medium would light travel the fastest?

question 21 options:

a. across a room

b. in a swimming pool

c. through outer space

d. through a railroad track

Light travel fastest in outer space, therefore the correct answer is option C.

We know that in outer space there is complete vacuum which means there is nothing to obstruct the path of light waves. Where as in swimming pool there is water that obstruct the light waves, in room there are air particle which obstruct the light waves, and in railroad track there is steel molecules which obstruct the path of light waves.

Therefore light waves travel faster in outer medium.

conservation of mass

mass before something happens = mass afterwards