Which statement correctly compares the speed of light
A.the speed of light through space is much greater than 3×10^8 m/s
B. This speed of light in glass this much greater than 3 x 10^8 m/s
C. The speed of light in glass is faster than the speed of light in space
D. The speed of light in glass is slower than the speed of light in space
The Correct Answer and Explanation is :
The correct answer is D. The speed of light in glass is slower than the speed of light in space.
Explanation:
The speed of light is influenced by the medium through which it travels. In a vacuum (space), the speed of light is approximately 3.00 × 10^8 meters per second. This is considered the maximum speed at which information or matter can travel. However, the speed of light decreases when it passes through other media like glass, water, or air.
1. Speed of Light in Space (Vacuum):
In a vacuum, the speed of light is constant at 3.00 × 10^8 m/s. This speed is a fundamental constant in physics, denoted by the symbol c. The vacuum provides no obstacles for light waves to interact with, allowing them to travel at this maximum speed.
2. Speed of Light in Glass:
When light enters a material like glass, it interacts with the atoms in the glass, causing a delay in its movement. This phenomenon is called refraction, where the light slows down and changes direction due to the denser medium. The speed of light in glass is typically around 2 × 10^8 m/s, which is slower than its speed in a vacuum. This reduction in speed occurs because the light waves are absorbed and re-emitted by the atoms in the glass, which causes a delay.
3. Why Glass Slows Light:
The material properties of glass—its refractive index—determine how much light slows down. The refractive index of glass typically ranges from 1.5 to 1.7, meaning light travels about 1.5 to 1.7 times slower in glass than in a vacuum.
4. Implications of Slower Light Speed:
This slowing of light in materials like glass is why we observe phenomena like bending of light when it enters or exits glass. It also explains why lenses and other optical devices are designed with specific materials to control light’s speed and direction.
In conclusion, the speed of light in glass is slower than the speed of light in space, making option D the correct choice.