Figure 4 shows a block (subsystem) diagram for a radio communication system - AQA - A-Level Physics - Question 3 - 2018 - Paper 8
Question 3
Figure 4 shows a block (subsystem) diagram for a radio communication system.
State the letter representing the subsystem in which you might find an induced emf b... show full transcript
Worked Solution & Example Answer:Figure 4 shows a block (subsystem) diagram for a radio communication system - AQA - A-Level Physics - Question 3 - 2018 - Paper 8
Step 1
State the letter representing the subsystem in which you might find an induced emf being generated.
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Answer
The letter representing the subsystem where an induced emf may be generated is D.
Step 2
State the letter representing the subsystem where the audio and radio waves are combined.
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Answer
The letter representing the subsystem where the audio and radio waves are combined is A.
Step 3
Explain why the signal strength at stage D is weak.
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Answer
The signal strength at stage D is weak due to:
The attenuation of the electromagnetic wave across the transmission path.
A small fraction of the radiated energy reaches the receiver, influenced by factors such as reflection from the ground, natural topography, and absorption in the atmosphere.
Step 4
Complete the graph in Figure 5 to represent the combined amplitude modulated (AM) signal.
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The combined AM signal graph should show the modulation of the carrier wave with amplitude variations corresponding to the modulating sine wave, forming an envelope around the carrier.
Step 5
Suggest whether all these stations can broadcast hi-fi music using the full audio frequency of 20 kHz.
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Answer
Not all stations can broadcast hi-fi music using the full audio frequency of 20 kHz. Given the frequency allocation of 540 KHz to 1600 KHz, the ability to transmit this frequency depends on the bandwidth each station has. Since a full audio frequency of 20 kHz would require a bandwidth of 40 kHz for each station, not all stations can afford to broadcast in this range due to potential overlap and cross-talk issues.
