Light year is an important unit of long distances (to measure the distance of stars, and terrestrial objects). One light year is the distance traveled by light in a vacuum in one year.
As velocity of light in vacuum is \(3 \times 10^{8} ms ^{-1}\) and \(1\) year \(=365 \times 24 \times 60 \times 60\) second,
Therefore, 1 light \(=3 \times 10^{8} \times(365 \times 24 \times 60 \times 60)\) metre
\(\therefore 1\) light year \(=9.46 \times 10^{15} m\)
A light-year is a measurement of distance and not time (as the name might imply). A light-year is a distance a beam of light travels in a single Earth year, which equates to approximately 6 trillion miles (9.7 trillion kilometers).
The ratio of the power of a light source \( S_1 \) to that of the light source \( S_2 \) is 2. \( S_1 \) is emitting \( 2 \times 10^{15} \) photons per second at 600 nm. If the wavelength of the source \( S_2 \) is 300 nm, then the number of photons per second emitted by \( S_2 \) is ________________ \( \times 10^{14} \).
The physical world includes the complications of the natural world around us. It is a type of analysis of the physical world around us to understand how it works. The fundamental forces that control nature are: