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Difficulty: MediumNegative Detail Identification

Sound-powered telephone systems provide critical emergency communication aboard naval vessels without relying on external electrical power. When a user speaks into the transmitter, acoustic sound waves vibrate a flexible diaphragm linked directly to a magnetic armature, generating weak electrical currents through electromagnetic induction. These self-generated electrical signals travel along dedicated, shielded two-wire circuits to the receivers of connected handsets. Because the system produces its own operating energy directly from voice vibrations, communication remains active even during complete shipboard electrical blackout. However, operational range is strictly limited compared to amplified networks, and having multiple talkers on the same circuit simultaneously diminishes audio clarity due to signal division.

According to the passage, which of the following is NOT true regarding sound-powered telephone systems?

  1. A
    They transmit voice signals across dedicated, shielded two-wire circuits.
  2. They rely on auxiliary emergency batteries to sustain communication during a power blackout.Answer
  3. C
    They generate operating current through electromagnetic induction caused by diaphragm movement.
  4. D
    They experience reduced sound clarity when several users speak concurrently on a single circuit.

Answer

Sound-powered telephone systems rely on auxiliary emergency batteries to sustain communication during a power blackout.
The passage explicitly states that sound-powered telephones function without external power and generate their own operating energy directly from the user's voice vibrations. Claiming that the system relies on auxiliary emergency batteries directly contradicts the text, making it the statement that is NOT true.

Step-by-Step Solution

1
Identify the negative qualifier in the question stem.
The prompt requires locating the statement that is NOT true based on the provided text.
Clarifying the negative constraint prevents mistakenly selecting statements that are factually supported by the text.
2
Cross-reference each answer choice against the facts in the passage.
Three options match stated details (shielded two-wire circuits, electromagnetic induction, signal reduction with multiple speakers), while one option asserts the use of auxiliary emergency batteries.
Verifying text evidence for each statement isolates the unsupported or contradicted claim.
3
Evaluate the contradictory statement against passage evidence.
The text states the system operates 'without relying on external electrical power' and 'produces its own operating energy', which directly refutes the claim of using emergency batteries.
Direct textual contradiction confirms the correct negative detail.

Key Concept

Negative Detail Identification
Estimated Time:1m 0s
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Negative Detail Identification

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