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Difficulty: Very hardExplicit Detail Retrieval

In his 1859 treatise on geomagnetic disturbances, astronomer Richard Christopher Carrington documented a temporal correlation between intense solar flares and widespread telegraph system disruptions. While Carrington posited that solar eruptive phenomena directly induced electric currents in terrestrial telegraph lines, his contemporary, Balfour Stewart, contended that the magnetic fluctuations were mediated by a magnetized atmospheric layer perturbed by solar radiation. Stewart noted that telegraph disruptions were non-uniform, occurring predominantly during nocturnal hours when atmospheric ionization normally declines, and were accompanied by abnormal auroral displays at low latitudes. Crucially, Stewart observed that wire currents persisted even after solar flares had visibly subsided, indicating that terrestrial atmospheric dynamics, rather than direct solar corpuscular radiation alone, sustained the inductive activity.

According to the passage, which of the following statements about Balfour Stewart's observations or hypotheses regarding geomagnetic disturbances is explicitly supported?

Select all that apply.

  1. Telegraph disruptions occurred predominantly during nighttime hours.Answer
  2. B
    Solar eruptive phenomena directly induced electric currents in telegraph wires without atmospheric mediation.
  3. Electric currents in telegraph wires continued even after solar flares were no longer visibly apparent.Answer

Answer

The statements confirming that telegraph disruptions occurred predominantly during nighttime hours and that electric currents in wires continued after solar flares ceased to be visibly apparent are both explicitly supported by the passage.
The passage explicitly states that Stewart noted telegraph disruptions occurred predominantly during nocturnal (nighttime) hours and observed that wire currents persisted even after solar flares had visibly subsided. Therefore, both the statement concerning nighttime disruptions and the statement regarding the persistence of currents after flares ceased to be visible are explicitly supported.

Step-by-Step Solution

1
Locate explicit mentions of Balfour Stewart's specific observations and claims in the text.
The text attributes three main findings/hypotheses to Stewart: (1) magnetic fluctuations were mediated by an atmospheric layer, (2) disruptions occurred predominantly during nocturnal hours, and (3) wire currents persisted after solar flares visibly subsided.
Explicit detail retrieval requires matching the question statements directly against facts explicitly asserted in the passage.
2
Evaluate the statement regarding nighttime telegraph disruptions.
Matches the text: 'Stewart noted that telegraph disruptions were non-uniform, occurring predominantly during nocturnal hours'.
'Nocturnal' is directly synonymous with 'nighttime'.
3
Evaluate the statement regarding direct solar induction without atmospheric mediation.
Inconsistent with Stewart's view; this was Carrington's position ('Carrington posited that solar eruptive phenomena directly induced electric currents... while Stewart contended that the magnetic fluctuations were mediated by a magnetized atmospheric layer').
Selecting this statement confuses Carrington's hypothesis with Stewart's counter-hypothesis.
4
Evaluate the statement regarding electric currents continuing after solar flares visibly subsided.
Matches the text: 'Stewart observed that wire currents persisted even after solar flares had visibly subsided'.
'Persisted' directly means continued, and 'visibly subsided' means no longer visibly apparent.

Key Concept

Explicit Detail Retrieval in Reading Comprehension
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Explicit Detail Retrieval

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