At a given point in its orbit, the moon is 2.4 x 105miles from earth. How long does it take light from a source on earth to reach a reflector on the moon and then return to earth

2.47 seconds.

Explanation:

We know that at this point, the distance between the moon and Earth is:

D = 2.3*10^5 miles

We want to know how much time does need the light to go from Earth to the moon and then return to Earth.

Here we can use the relationship:

Time = Distance/Speed

Distance is equal to two times the distance between Earth and the moon (because the path is traveled two times), then:

Distance = 2*(2.3*10^5 miles) = 4.6*10^5 miles.

The speed is equal to the speed of light, we know that this is:

Speed = 186,282 mi/s

Then the time will be:

time = (4.6*10^5 mi)/( 186,282 mi/s) = 2..47 s

The light needs 2.47 seconds to go from Earth to the moon and come back.

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.