Difference Between Speed of Light and Sound

Speed of Light vs Sound

Speed of light and speed of sound are two very important aspects of waves discussed under physics. There is a huge significance of these concepts in fields ranging from communication to relativity and even quantum mechanics. This article will try to compare and discuss the differences between speed of sound and light.

Speed of Sound

To understand the significance of speed of sound, one must first understand sound. Sound is actually a wave. To be precise sound is a longitudinal wave. A longitudinal wave oscillates the particles so that the oscillation is parallel. The amplitude of these oscillations decides the intensity of sound (how loud the sound is). It is obvious that to create a sound there must be a mechanical oscillation. Sound can be considered as a set of pressure pulses. It must be noted that sound always requires a medium to travel. There will be no sound in a vacuum. The speed of sound is defined as the distance the sound wave travels through an elastic medium per unit time. The speed of sound in a medium is equal to the square root of the coefficient of stiffness divided by the density of the medium (v = (C / ρ)1/2). There are several experiments to measure the speed of sound. Some of these methods are single shot timing method and Kundt’s tube method.

Speed of Light

Speed of light is a very important concept in modern physics. It is believed to be the only absolute parameter in the universe. According to the theory of relativity the speed of light is the maximum velocity any object can hypothetically obtain. It can be shown that any object having a rest mass cannot obtain speed of light as it requires an infinite amount of energy. To get the idea of the speed of light, a good idea about light is essential. Light is a form of electromagnetic wave. It does not require a medium to travel. However, it is theoretically suggested and practically proved that light also has particle characteristics. This is known as the wave particle duality of matter. Every matter has this duality. As said earlier the theory of relativity suggests the relative velocity between any two objects cannot take velocities higher than the speed of light. This acts as a natural limit. It must be noted that speed of light can be reduced due to impedance of a media. This causes events such as refraction. The colour of the light depends on the wavelength of the wave. In the particle theory of light, the light waves come in small packets known as photons. The value of the speed of light in free space is 299,792,458 meters per second. This value can be obtained using several methods. These methods include Romer method, which uses astronomical objects to measure the speed. Several methods measure frequency and wavelength of several light beams separately and use them to calculate the speed of light.

What is the difference between speed of light and speed of sound?

• Sound cannot travel in vacuum while light can.

• Speed of light in a vacuum is the highest velocity any object can obtain. The speed of sound does not hold any such significance.

• The speed of sound is always lower than the speed of light.