A marine engineer tests a radio communication system for an unmanned research boat. Fig. 1 shows a radio aerial on a cliff sending a signal to the boat. The...
Question 1 Report
A marine engineer tests a radio communication system for an unmanned research boat. Fig. 1 shows a radio aerial on a cliff sending a signal to the boat. The distance from the aerial to the boat is 24 km. The electromagnetic radio waves travel through air at 3.0 × 108 m/s. The boat uses the received signal to change speed and direction.
(a) Describe how the radio signal transfers energy from the aerial to the receiver on the boat. [2]
(b) Calculate the time taken for the radio waves to travel from the aerial to the boat. [3]
(c) State one reason why radio waves are suitable for communication with the boat. [1]
(d) Explain why a very large hill between the aerial and the boat may reduce the strength of the received signal. [2]
Answer Details
(a) The transmitting aerial produces electromagnetic radio waves. [1] These waves carry energy through the air to the receiving aerial on the boat. [1]
(b) \[24\text{ km}=24\,000\text{ m}\] [1]
\[t=\frac{d}{v}=\frac{24\,000\text{ m}}{3.0\times10^8\text{ m/s}}\] [1]
\[t=8.0\times10^{-5}\text{ s}\]
The travel time is \(8.0\times10^{-5}\text{ s}\). [1]
(c) Radio waves are suitable because they can travel long distances through air and carry information. Either stated reason is acceptable. [1]
(d) A large hill blocks or absorbs some radio waves. [1] Less wave energy reaches the receiving aerial, so the received signal is weaker. [1]
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