Physics A-Level
Light-year (ly)
What Light-year (ly) means in Physics A-Level, as defined for OCR.
Definition of Light-year (ly)
Check what you remember
Read the wording for your board, then hide it and explain Light-year (ly) in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: OCR
The distance light travels in a vacuum in one year, about 9.46 × 10¹⁵ m, convenient for distances to stars and galaxies.
Topics that use Light-year (ly)
- Cosmology (OCR A-Level)
Related terms
- Age of the universe
- Astronomical distance units
- Baseline
- Big Bang nucleosynthesis
- Big Bang theory
- Cosmic microwave background
- Cosmic microwave background radiation
- Cosmological redshift
Using Light-year (ly) in the exam
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