• 4 months ago
Transcript
00:00Hi friends! Today we will learn more about sound. So let's get started.
00:09Sound. As sound gives us information about our environment.
00:16Sound helps us to give instruction. We can call out for help in danger.
00:24We can converse with our near and dear one.
00:28Sound is a very important part of our life.
00:34Now, let's learn how do sound waves travel?
00:39Or the transmission of sound.
00:43Every sound is produced by some vibration.
00:47And vibration is a back and forth movement of some object.
00:54Like the back and forth movement of our vocal cords when we speak.
00:59Back and forth movement of the string of guitar, etc.
01:04So, sound is a vibration or it's a result of some vibration.
01:13Now we have to see how does the sound produced by any vibration reaches our ears.
01:20Or how does sound travel?
01:24Sound travels in the form of waves.
01:27And there are two types of waves.
01:30Transverse waves. Longitudinal waves.
01:36Longitudinal waves.
01:39In longitudinal waves, vibrations moves parallel to the direction of the wave.
01:46Here the particles move side to side.
01:52Here you see the movement of slinky.
01:56Here the movement of wave in the slinky is an example of longitudinal waves.
02:05Next is the transverse wave.
02:09Here the vibration travels perpendicular to the movement of the wave.
02:14Or the particles move up and down.
02:17And it resembles the waves in the sea.
02:22Sound waves travels as longitudinal waves in air and water.
02:28And in solids.
02:30Sound can travel both as longitudinal as well as transverse wave.
02:37Now we will learn part of different types of waves.
02:43Parts of longitudinal waves.
02:46Parts of transverse waves.
02:49Let's first learn the parts of a transverse wave.
02:55First is the resting point.
02:58It is the line that runs in the middle of the wave.
03:02It divides the wave into two equal halves.
03:06Next part of the wave are crests and troughs.
03:11Troughs is the lowest point in a wave.
03:14Crest is the highest point in a wave.
03:18In this wave we have three crests and three troughs.
03:24Next is the wavelength of a transverse wave.
03:29It is the measurement of distance between two crests or two troughs.
03:36Like this, that is between two points, this is one wavelength.
03:42You can also measure it here, that is between two troughs.
03:51Wavelength is the distance between, covered by one consecutive crest and trough.
04:01Next is the amplitude of a transverse wave.
04:05It's same as the height of the wave.
04:08And in order to measure height of the wave,
04:11we measure the length from the resting line to the top of the crest.
04:16Or, other way is to measure the amplitude,
04:20is to measure the distance between the resting line to the bottom of the trough.
04:25Both are correct.
04:29Now next, learn what is the frequency of the wave.
04:33It's the number of wavelengths produced in a given amount of time.
04:39Now let's learn it with an example.
04:43Let's see two different transverse waves produced in one second.
04:50Here we have two transverse waves produced in one second.
04:55In first wave, only two waves are there.
05:00And in the second wave, we can see there are many wavelengths.
05:05Let's count.
05:08Here we have five wavelengths produced in one second.
05:13So first one has lower frequency,
05:17then the second one has more frequency,
05:20that is, more number of wavelengths are produced in one second.
05:26And we know what's a wavelength.
05:29It's a distance between two consecutive crests or two consecutive troughs.
05:34Or, the distance between covered by one crest and one trough.
05:40So, the wave which has visibly more number of crests and troughs has more frequency.
05:48So we have learned parts of transverse waves.
05:52Now let's learn the parts of the longitudinal wave.
05:57And in case of the longitudinal wave,
06:00particles travel side to side in the direction of the wave.
06:06Let's first learn what is compression in case of longitudinal waves.
06:13Compression is that part of the wave where particles are crowded together or very close to each other.
06:22Like in this wave, you can see at three places there are particles gathered together.
06:30So there are three compression in this wave.
06:34Next is what is rare fraction.
06:38It's the places in the wave where particles are not close to each other.
06:44They are at more distances than compression.
06:48So, you can clearly see in this wave there are three rare fraction in this wave.
06:57Next is wavelength in longitudinal wave.
07:01Like we learned in case of transverse wave,
07:04wavelength is the distance between two consecutive troughs or crests.
07:10Similarly, in longitudinal waves,
07:14wavelength is the distance between two consecutive rare fraction or two consecutive compression.
07:23So kids, today we learned longitudinal and transverse waves,
07:29and also their different parts.
07:33Now you may go ahead and take a quiz to learn more.
07:37Bye-bye.
07:40For more information, visit www.nasa.gov