A 6,000-km undersea glass fiber phone line crosses the Atlantic ocean connecting the US and France. (a) How long does it take for a message to transverse this link? (b) How long does it take for a message to travel from US to France by using a satellite link? The satellite is stationed about 22,000 miles above the earth between the US and France. (c) Will two people having a conversation across these two different links notice the travel delays?

Message will travel through the fibre at the speed of 3 x 10⁸ m / s which is also the speed of light.

a) Time for a message to travel from US to France by using glass fibre link

time = distance / speed

= 6000 x 1000 / 3 x 10⁸

=.02 s.

b)

22000 miles = 1.6 x 22000

= 35200 km

Time for a message to travel from US to France by using a satellite link

time = distance / velocity

distance = 2 x √ (35200² + 3000²)

= 2 x 35327 km

=.7 x 10⁸ m.

time =.7 x 10⁸ / 3 x 10⁸

=.233 s

c)

Difference of time =.233 -.02

=.213 which is more than 1/6 s for which effect of hearing stays in the brain, which is called persistence of vision. So they will be heard as different sounds.