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 ________________ \( \times 10^{14} \).
Two light beams fall on a transparent material block at point 1 and 2 with angle \( \theta_1 \) and \( \theta_2 \), respectively, as shown in the figure. After refraction, the beams intersect at point 3 which is exactly on the interface at the other end of the block. Given: the distance between 1 and 2, \( d = \frac{4}{3} \) cm and \( \theta_1 = \theta_2 = \cos^{-1} \left( \frac{n_2}{2n_1} \right) \), where \( n_2 \) is the refractive index of the block and \( n_1 \) is the refractive index of the outside medium, then the thickness of the block is …….. cm.
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: