87 lines
4.1 KiB
Markdown
87 lines
4.1 KiB
Markdown
G3A – Sunspots and solar radiation; geomagnetic field and stability indices
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- [[G3A01]] (A)
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How does a higher sunspot number affect HF propagation? #card
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- A. Higher sunspot numbers generally indicate a greater probability of good propagation at higher frequencies
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- B. Lower sunspot numbers generally indicate greater probability of sporadic E propagation
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- C. A zero sunspot number indicates that radio propagation is not possible on any band
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- D. A zero sunspot number indicates undisturbed conditions
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- [[G3A02]] (B)
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What effect does a sudden ionospheric disturbance have on the daytime ionospheric propagation? #card
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- A. It enhances propagation on all HF frequencies
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- B. It disrupts signals on lower frequencies more than those on higher frequencies
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- C. It disrupts communications via satellite more than direct communications
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- D. None, because only areas on the night side of the Earth are affected
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- [[G3A03]] (C)
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Approximately how long does it take the increased ultraviolet and X-ray radiation from a solar flare to affect radio propagation on Earth? #card
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- A. 28 days
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- B. 1 to 2 hours
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- C. 8 minutes
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- D. 20 to 40 hours
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- [[G3A04]] (D)
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Which of the following are the least reliable bands for long-distance communications during periods of low solar activity? #card
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- A. 80 meters and 160 meters
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- B. 60 meters and 40 meters
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- C. 30 meters and 20 meters
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- D. 15 meters, 12 meters, and 10 meters
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- [[G3A05]] (D)
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What is the solar flux index? #card
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- A. A measure of the highest frequency that is useful for ionospheric propagation between two points on Earth
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- B. A count of sunspots that is adjusted for solar emissions
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- C. Another name for the American sunspot number
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- D. A measure of solar radiation with a wavelength of 10.7 centimeters
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- [[G3A06]] (D)
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What is a geomagnetic storm? #card
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- A. A sudden drop in the solar flux index
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- B. A thunderstorm that affects radio propagation
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- C. Ripples in the geomagnetic force
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- D. A temporary disturbance in Earth’s geomagnetic field
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- [[G3A07]] (D)
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At what point in the solar cycle does the 20-meter band usually support worldwide propagation during daylight hours? #card
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- A. At the summer solstice
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- B. Only at the maximum point
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- C. Only at the minimum point
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- D. At any point
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- [[G3A08]] (D)
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How can a geomagnetic storm affect HF propagation? #card
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- A. Improve high-latitude HF propagation
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- B. Degrade ground wave propagation
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- C. Improve ground wave propagation
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- D. Degrade high-latitude HF propagation
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- [[G3A09]] (A)
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How can high geomagnetic activity benefit radio communications? #card
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- A. Creates auroras that can reflect VHF signals
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- B. Increases signal strength for HF signals passing through the polar regions
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- C. Improve HF long path propagation
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- D. Reduce long delayed echoes
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- [[G3A10]] (C)
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What causes HF propagation conditions to vary periodically in a 26- to 28-day cycle? #card
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- A. Long term oscillations in the upper atmosphere
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- B. Cyclic variation in Earth’s radiation belts
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- C. Rotation of the Sun’s surface layers around its axis
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- D. The position of the Moon in its orbit
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- [[G3A11]] (D)
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How long does it take a coronal mass ejection to affect radio propagation on Earth? #card
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- A. 28 days
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- B. 14 days
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- C. 4 to 8 minutes
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- D. 15 hours to several days
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- [[G3A12]] (B)
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What does the K-index measure? #card
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- A. The relative position of sunspots on the surface of the Sun
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- B. The short-term stability of Earth’s geomagnetic field
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- C. The short-term stability of the Sun’s magnetic field
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- D. The solar radio flux at Boulder, Colorado
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- [[G3A13]] (C)
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What does the A-index measure? #card
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- A. The relative position of sunspots on the surface of the Sun
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- B. The amount of polarization of the Sun’s electric field
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- C. The long-term stability of Earth’s geomagnetic field
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- D. The solar radio flux at Boulder, Colorado
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- [[G3A14]] (B)
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How is long distance radio communication usually affected by the charged particles that reach Earth from solar coronal holes? #card
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- A. HF communication is improved
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- B. HF communication is disturbed
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- C. VHF/UHF ducting is improved
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- D. VHF/UHF ducting is disturbed
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