One light year is equal to________________?
Correct answer: A. 9.5 x 10^15m
- A. 9.5 x 10^15m
- B. 9.5 x 10^15sec
- C. 9.5 x 10^15Km
- D. 9.5 x 10^15cm
Explanation
A light-year is a distance, not a time: 1 light-year = speed of light × 1 year = (3.00 x 10^8 m s-1)(3.156 x 10^7 s) ≈ 9.46 x 10^15 m, rounded to 9.5 x 10^15 m. Students may choose B because the word year suggests seconds, but a light-year measures how far light travels in one year.
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About Optics
Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
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