The correct option is n = c/v.
Explanation
The absolute refractive index of a medium is a measure of its optical density, which determines how much the speed of light is reduced when propagating through it compared to a vacuum. It quantifies the bending of light as it enters the medium from a vacuum.
Analysis:
- The absolute refractive index ($n$) is mathematically defined as the ratio of the speed of light in a vacuum ($c$) to the speed of light in the medium ($v$).
- The relationship is expressed by the equation:
$n = \frac{c}{v}$ - Since the speed of light in a vacuum ($c \approx 3 \times 10^8$ m/s) is the maximum possible speed in the universe, $c$ is always greater than or equal to $v$. Consequently, the absolute refractive index is always greater than or equal to 1 ($n \geq 1$).
- n = c/v correctly represents this definition. Options n = v/c, n = c·v, and n = c − v are incorrect formulations.
Key Takeaway:
The absolute refractive index is a dimensionless quantity given by $n = c/v$, indicating how much slower light travels in a medium compared to a vacuum.