All flashcards
Flashcard 1: What is the main reason distant stars usually look dimmer than nearby stars?
Answer: Their light spreads out over a larger area. Light energy dilutes as it spreads through space.
Flashcard 2: Choose the correct comparison: If Star A is closer than Star B, Star A appears brighter or dimmer?
Answer: Brighter. Closer distance means higher apparent brightness.
Flashcard 3: What term names how bright a star appears to an observer on Earth?
Answer: Apparent brightness. Measures brightness as seen from Earth, not the star's actual output.
Flashcard 4: What term names how much light a star actually gives off (its true brightness)?
Answer: Luminosity. The star's actual light output, independent of viewing distance.
Flashcard 5: Which option best completes the statement: Light spreads out as it travels, so far stars look .
Answer: dimmer. Light intensity decreases as it spreads over larger areas.
Flashcard 6: Identify which star appears brighter from Earth if both have the same luminosity: the nearer star or the farther star?
Answer: The nearer star. Same luminosity means distance alone determines apparent brightness.
Flashcard 7: What is the main reason a very luminous star can still look dim from Earth?
Answer: It is very far away. Distance reduces apparent brightness despite high luminosity.
Flashcard 8: What is the main reason a less luminous star can look bright from Earth?
Answer: It is close to Earth. Proximity compensates for lower actual light output.
Flashcard 9: Choose the correct statement: Apparent brightness depends on distance, luminosity, or both?
Answer: Both distance and luminosity. Apparent brightness = luminosity divided by distance squared.
Flashcard 10: Which option best completes the statement: Apparent brightness decreases with distance because light energy spreads over a larger .
Answer: area. Light energy is conserved but diluted over expanding spherical surfaces.
Flashcard 11: Identify the correct comparison: Two stars have equal luminosity; which one has greater apparent brightness if it is closer?
Answer: The closer star has greater apparent brightness. Inverse square law favors the closer star when luminosity is equal.
Flashcard 12: Identify the correct comparison: Two stars have equal apparent brightness; which one is more luminous if it is farther away?
Answer: The farther star is more luminous. Must compensate for greater distance with higher light output.
Flashcard 13: Which statement is correct: If two identical stars differ only in distance, the farther one appears brighter or dimmer?
Answer: The farther star appears dimmer. Greater distance always reduces apparent brightness.
Flashcard 14: What is the main relationship between a star's distance from Earth and its apparent brightness?
Answer: Greater distance makes a star appear dimmer. Light spreads out as it travels, reducing intensity per unit area.
Flashcard 15: What term names how bright a star appears from Earth (as seen by an observer)?
Answer: Apparent brightness. Describes brightness as observed from Earth, not the star's actual output.
Flashcard 16: Which option best describes why distant stars look dimmer: light spreads out or stars make less light?
Answer: Light spreads out over a larger area. Light energy disperses over increasing surface area with distance.
Flashcard 17: What term names how much light a star actually gives off (its true light output)?
Answer: Luminosity. The star's actual light output, independent of viewing distance.
Flashcard 18: Which quantity stays the same when only distance changes: apparent brightness or luminosity?
Answer: Luminosity stays the same. A star's actual light output doesn't change with viewing distance.
Flashcard 19: Which option is correct: A nearby low-luminosity star can appear brighter than a distant high-luminosity star?
Answer: Yes, distance can make a nearby star appear brighter. Proximity can overcome differences in actual light output.
Flashcard 20: Which star appears brighter if two stars have the same luminosity: one at 2 units or one at 4 units?
Answer: The star at 2 units appears brighter. Closer star appears brighter due to inverse-square law.
Flashcard 21: Which star appears dimmer if two stars have the same luminosity: one at 3 units or one at 6 units?
Answer: The star at 6 units appears dimmer. Double the distance means one-fourth the brightness.
Flashcard 22: What happens to apparent brightness if distance is cut in half for the same star?
Answer: It becomes 4 times brighter. Halving distance means 22=4 times the brightness.
Flashcard 23: Which option is correct: A star can look dim but be very luminous, or dim means low luminosity?
Answer: A star can look dim but be very luminous. Distance can make very bright stars appear faint to observers.
Flashcard 24: Which is brighter for the same star: at distance d or at distance 2d?
Answer: At distance d. Half the distance means four times brighter.
Flashcard 25: Which quantity changes with distance: apparent brightness or luminosity?
Answer: Apparent brightness changes with distance. How bright we see a star depends on our distance from it.
Flashcard 26: Choose the correct idea: Does distance change a star’s luminosity or only how bright it appears?
Answer: Distance changes only how bright it appears, not its luminosity. Luminosity is intrinsic; only appearance changes with distance.
Flashcard 27: What term describes how bright a star appears to an observer on Earth?
Answer: Apparent brightness. Brightness as seen from Earth, not the star's true output.
Flashcard 28: Which is a better predictor of apparent brightness: distance or a star’s name?
Answer: Distance. Distance directly affects how bright stars appear.
Flashcard 29: Identify the best explanation for why nearby stars often appear brighter than distant stars.
Answer: Less distance means less spreading of the same light. The same light energy is concentrated in a smaller area.
Flashcard 30: What term means how much light a star actually gives off?
Answer: Absolute brightness (luminosity). The actual light output, independent of distance.