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IB Physics HL B.1.15 Apparent brightness Question Bank

Practise IB Physics HL B.1.15 by defining apparent magnitude and explaining how combined luminosity changes a binary star's observed brightness.

Syllabus
First assessment 2025
Course
Physics HL
Level
HL

Exam points

  • Define apparent magnitude as a logarithmic measure of how bright a star appears to an observer.
  • Explain how adding a companion's luminosity changes the apparent brightness of a binary system.

B.1.15—Apparent brightness question 1

[Maximum number: 1]

Alpha Centauri A and B form the closest binary star system to the Earth. This binary star system is the third brightest stellar object in the night sky.

Arcturus is the fourth brightest star in the night sky. Its apparent brightness is slightly greater than that of the star Alpha Centauri A.

Outline why the binary star system Alpha Centauri appears brighter than Arcturus.

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