Communicating with waves — return questions

1. suggest / explain

(a) A cargo ship sails east across the Pacific Ocean, near the equator, from the Philippines to Peru. Its satellite phone works through geostationary satellites, and part of the way across it switches from one satellite to another. Suggest why. (b) Supplement. In the port office, a printer linked by Bluetooth prints from a laptop in the next room, through one wall. From a room four walls away, it prints nothing. Explain why.

(a) Why the phone switches satellites

(b) Supplement: why the printer prints nothing

2. explain

Supplement. A concert is broadcast by two radio stations. Station F broadcasts it on FM, as an analogue signal; station D broadcasts it on DAB, as a digital signal. (a) Match each statement to the station, or stations, it is true of. (b) A family drives away from both transmitters. The FM programme gets more and more hiss, but the DAB programme stays perfectly clear until, quite suddenly, it breaks up. Explain the difference.

Write the number of the matching option.

1. Station D only
2. Both stations
3. Station F only

• Its signal began as a varying voltage from a microphone at the concert: ______
• The radio in the car decides whether each pulse it receives is on or off: ______
• The wave it sends out varies smoothly, by any amount, as the sound does: ______
• Its signal picks up noise on the way to the car: ______

(b) Why FM hisses more and more, but DAB stays clear and then breaks up