Difference Between Radio Waves and Sound Waves

Main Difference – Radio Waves vs. Sound Waves

Sounds are made of waves and radios produce sound. However, when we talk about radio waves, we are not talking about the sound waves produced by the radio. Rather, we are talking about the waves that transmit radio signals. The main difference between radio waves and sound waves is that radio waves are a type of electromagnetic wave that can travel when there is no medium, whereas sound waves are a type of mechanical wave that cannot travel if there is no medium.

What are Radio Waves

Radio waves are electromagnetic waves. These are waves composed of electric and magnetic fields, which are oscillating at right angles to each other. The energy of an electromagnetic wave propagates at a direction at right angles to the oscillations in both the electric and magnetic fields. In the diagram below, the black arrows show the oscillations in electric and magnetic fields. The direction of propagation of the wave is indicated by the grey arrow.

Difference Between Radio Waves and Sound Waves - Electromagnetic_Waves

Oscillations in an electromagnetic wave.

Since the actual oscillations take place at right angles to the direction of wave propagation, radio waves are transverse waves. Since radio waves are not mechanical, they do not need a medium to travel in; they can travel even in a vacuum. Like all types of electromagnetic waves, radio waves travel at a speed of about 300 000 km per second in a vacuum. When radio waves enter into other material, they slow down a little.

When you tune a radio to listen to a particular frequency, the radio takes in the signals at that frequency. Then, the radio’s circuits convert the electric signals into the movements in the speaker. These movements create movements in the air in front of the speaker, recreating the sound.

Difference Between Radio Waves and Sound Waves - Old_Radio

An old radio

What are Sound Waves

Sound waves are mechanical longitudinal waves. “Mechanical” means that sound waves must have a medium to pass through. The sound is really composed of the back-and-forth motion of molecules that make up the medium. These back-and-forth motions of molecules cause them to come towards each other, forming compressions. Then, the molecules move away from each other, forming rarefactions. This happens over and over again. Humans can “hear” sounds when a molecule undergoes this back-and-forth motion about 20-20 000 times per second. We say that sound waves are “longitudinal” because the movement of molecules take place parallel to the direction that the sound travels in. The speed of sound in a medium depends on the density of the material. Sound travels through air at room temperature and pressure at a speed of about 340 m per second. Typically, sound can travel faster in liquids and even faster in solids. Sound can travel through diamond at a speed of about 12 km per second1.

Difference Between Radio Waves and Sound Waves - Sound_Waves

Sound is really a pressure wave, composed of compressions and rarefactions in the molecules that make up the medium.

Difference Between Radio Waves and Sound Waves

Medium

Radio waves are electromagnetic waves that can travel through a vacuum.

Sound waves are mechanical waves that require a medium to travel through.

Wave classification

Radio waves are transverse waves. They can be polarised.

Sound waves are longitudinal waves. They cannot be polarised.

Speed

Radio waves are much faster, typically travelling millions of metres per second.

Sound waves are much slower, typically travelling a few hundred or a few thousand metres per second.

 

References

1. Nave, R. (2012). Speed of Sound. Retrieved September 17, 2015, from HyperPhysics Concepts

Image Courtesy

“Electromagnetic wave” by User:LennyWikidata (Own work) [], via

“Dad’s Radio” by PROAlan Levine (Own work) [], via 

“Diagram showing physical manifestation of a sound wave through air from a speaker to a human ear” by Pluke (Own work) [], via  (modified)

About the Author: Nipun


Related pages


is the death penalty ethicaldifference between shark and dolphinhow is wrought iron different from steelsentences with concrete and abstract nounsfigurative vs literal language worksheetschutney or relishdefine autosomal chromosomedefine megaloblastic anaemiadefinition of receptive languagedefinition for symbolism in literatureardvark vs anteaterdifference sushi sashimidestructive and constructive wavesdifference between duchess and countesswhat is the difference between a tortoise and a turtlepast participle of ledherbivore vs carnivoreempiricism rationalismdefinition of absorbancewhat is a phototrophcultural assimilation examplesvernier caliper least count formula pdfmadame definehow does a concrete noun differ from an abstract noundifference between voltmeter and ammetermultinational corporation meaningshruti smritidefine mitosis and meiosishigh density polyethylene vs low density polyethyleneaisle isleexample of a predicate nominativemeaning of informal lettermeaning of confectionarydifferent types of molassessynecdoche examples in literaturehobbies meaning in hindithe difference between ma and mscwhat is difference between copd and emphysemawhat is a vinyl halideoxymoron defmolecular formula of maltosekinematics vs dynamicsdifference between yorkie and silky terriercouscous definitionwhat is the difference between duke and princecompare and contrast conductors and insulatorsintegrity vs honestycast iron and wrought irondifference between frog & toadwhat are predicate nominativesstatic friction definedegree of polymerization calculationdifference between aquatic and terrestrial ecosystemshomophone for polewhat is the difference between an adjective and an adverbdefine complainsdifference between seminar and workshopstarch cellulose and glycogendifference between blackstrap molasses and regular molassespresent value bond calculatorseed structure of monocot and dicotdifference between a cougar and a pantherwhat is the difference between macro and micronutrientsmeaning of pulses in foodpronunciation and annunciationdifference between b12 deficiency and pernicious anemiahyperosmotic solutionrolling friction and sliding frictionwhat is a protostomeexamples of catabolismexamples of linking and action verbswhat is the difference between inquire and enquiredefine empirical and molecular formulawolf versus coyotecommiserate in a sentence