Understanding Sound and Light: Properties and Behaviors
Understanding Sound and Light
Sound Waves
Audible sounds are produced when a body vibrates at a frequency between 20 Hz and 20,000 Hz.
- A wave is a disturbance of the medium that propagates through space.
- In a wave, energy is propagated, not matter.
- Sound waves consist of a succession of compressions and rarefactions (high and low pressure).
- Sound needs a medium (solid, liquid, or gas) to propagate.
- Sound travels through air at a speed of approximately 340 m/s at normal temperature. The speed is higher in most solids and liquids.
- The reflection of sound produces the phenomena of echo and reverberation.
- To avoid echoes, the reflecting surface should be at least 17 meters away from the sound source. This is because the echo occurs when the reflected sound arrives at the listener’s ear more than 0.1 seconds after the original sound. The distance can be calculated as: V = s / t, therefore s = v * t = 340 m/s * 0.1 s = 34m
Light Waves
Light is electromagnetic radiation that is visible to the human eye. Light propagates as a wave at a speed of 300,000 km/s in a vacuum. In any other medium, light travels at a slower speed.
- Light travels in straight lines, and shadows occur when its path is partially blocked by an obstacle.
- The reflection of light is the change in direction of a light ray when it strikes a surface:
- Diffuse reflection allows us to see the shapes of objects.
- Specular reflection explains the formation of images in mirrors.
- In reflection, the angle of incidence of the light is equal to the angle of reflection (the law of reflection).
- The refraction of light is the change in direction of light rays as they pass from one medium to another with different speeds.
- When light interacts with a material body, it can be reflected, absorbed, or transmitted through the body. All bodies partially reflect light in either a specular or diffuse manner. Opaque bodies absorb light, transparent bodies transmit light, and translucent bodies scatter light.
- White light is produced by superimposing the primary colors: red, green, and blue.
- The color of an opaque body is the color it reflects, absorbing all others.
- The color of a transparent body is the color it transmits, absorbing all others.
- The color that results after combining pigments is due to subtractive color mixing.