Although some international telephone signals are sent via satellites in geostationary orbits, most are sent along cables on the Earth’s surface. This reduces the time delay between sending and receiving the signal. Estimate this time delay for communication via a satellite, and explain why it is less significant when cables are used.

You will need the following:
. Radius of geostationary orbit = 42,300 km
. Radius of Earth = 6400 km
. Speed of electromagnetic waves in free space c = 3.0 × 10⁸ m s⁻¹