When light travels from air to glass, what happens to its speed?
AIncreases
BDecreases
CRemains same
DBecomes zero
Answer:
B. Decreases
Read Explanation:
- Refractive Index: Light speed depends on the optical density of the medium. Glass has a higher refractive index (approximately 1.5) compared to air (approximately 1.0003).
- Velocity Change: When light transitions from a rarer medium (air) to a denser medium (glass), its velocity decreases. Conversely, it increases when moving from a denser to a rarer medium.
- Constant Speed: The speed of light in a vacuum is defined as c ≈ 3 × 10⁸ m/s. In any other medium, the speed v is given by the formula v = c / n, where n is the refractive index.
- Frequency vs. Wavelength: As light enters a denser medium, its frequency remains constant because it is determined by the source. To compensate for the reduction in speed, the wavelength of light decreases.
- Bending of Light: This change in speed causes the light ray to refract or bend towards the normal when entering glass from air.
- Optical Density: Glass is considered an optically denser medium than air, meaning it offers more resistance to the propagation of electromagnetic waves.