Science Question Answer (1 Marks)

The number 256 on tuning fork signifies the frequency of tuning fork.

Supersonic aircrafts.

Vacuum.

Frequency.

Longitudinal waves.

Porpoise produces ultrasonic waves.

Ultrasonic sound waves.

1. Loudness.
2. Pitch.
3. Timbre or Quality.

Infrasonic waves: 10Hz, 18Hz
Ultrasonic waves: 30,000Hz, 50,000Hz

Quality or timbre.

An echo is heard sooner in water because the speed of sound in water is higher than the speed of sound in air.

The conclusion from the observation is that the prongs of tuning fork are vibrating, and the vibrating prongs carry energy which gets transmitted to surrounding medium.

Ear drum starts vibrating when outside sound falls on it.

Longitudinal (sound) waves.

Megaphone.

The frequency in hertz is equal to the number of waves produced per second. In this case, 20 waves are produced per second, so the frequency of sound waves is 20 hertz.

Sound is a longitudinal wave.

Soundboard works on the principle of reflection of sound.

Infrasonic sound waves.

Speed of sound is more in steel (solid medium) as compared to water (liquid medium).

Light travels much faster than sound. Due to this, the flash of lightning is seen first and the sound of thunder is heard a little later.

A stethoscope, based on the principle of reflection of sound, is used by doctors to listen to our heartbeats.

Sound travels fastest in solids.

Ears enable us to hear sounds.

Echo is repetition of sound caused by the reflection of sound waves.

It is more convenient to put the ear to the track to hear a train approaching from far away because sound travels faster in solids than in air.

Radio waves are used to communicate with one another on moon.

Longitudinal wave.

The reflection of sound leads to formation of echoes.

Supersonic Speed.

No, we cannot hear infrasonic waves and ultrasonic waves. That’s because the frequencies of both these waves fall beyond the human audible range of frequencies.

The sound waves in air are longitudinal waves.

SONAR is used to find the depth of sea by using ultrasonic sound waves.

Infrasonic sound.

Sound travels faster in iron (being a solid medium).

Sound travels fastest in steel (solid medium).

Yes, sound can travel through iron and as well as water.

Supersonic speed refers to the speed of an object which is greater than the speed of sound.

The three tiny bones present in the middle part of ear are: anvil, hammer and stirrup.

As the frequency increases the pitch of the sound also increases.

• Slowest - Sound
• Fastest - light

Ultrasound scans are used to monitor the growth of developing baby in the uterus of the mother.

The persistence or sound in a big hall or auditorium is called reverberation.

An object should vibrate in order to produce sound.

Stirrup.

Soundboard is a concave board which is kept behind the speaker on the stage of a big hall.

1. Megaphone and bulb horn.
2. Stethoscope.
3. Soundboard.

• Solid - table.
• Liquid - water.
• Gas - air.

Ear canal.

An ultrasound scan for fetus is better than X-rays because X-rays can damage the delicate body cells of the fetus.

Transverse and Longitudinal waves.

Tuning fork is used to produce sound in laboratory experiments.

3. Speed of sound in copper = 3750m/s

1. Speed of sound in aluminium = 5100m/s

Sound waves in air: Longitudinal, Compression, Rarefaction.
Water waves: Transverse, Crest, Trough.

Supersonic is used to denote a speed greater than the speed of sound.

Eustachian tube.

Sound travels slowest in gases.

Velocity of sound = Frequency × wavelength
Speed of sound in air is constant.
Hence, frequency × wavelength = constant
If frequency is doubled, wavelength is reduced to half.

Ultrasonic sounds.

The function of three tiny bones in the ear is to increase the strength of vibrations coming from the ear drum before passing them onto the inner ear.

Vocal cords vibrate in our voice box when we talk.

1. Loudness.
2. Pitch.
3. Timbre.

The loudness of sound is measured in decibel. Its symbol is dB.

The sound frequencies that cannot be heard by a human ear are 10Hz, 15Hz and 40,000Hz.

No, sound cannot travel through vacuum.

Bat navigates and finds its food by echolocation.

It is common observation that in the rainy season, the flash of lightning is seen first and the sound of thunder is heard a little later. That’s because, speed of light is very high as compared to speed of sound in air.

Pitch helps us to distinguish between a man’s voice and a woman’s voice, even without seeing them.

Curtains and carpets can make our big room less echoey.

Transverse waves.

SI unit of frequency is hertz.

Transverse wave.

Auditory nerve.

A megaphone is used to address a small gathering of people.

Sound Navigation And Ranging.

The loudness decreases with the decrease in the amplitude of sound.

Sound travels faster in hydrogen (speed of sound in hydrogen is 1284m/s).

Hammer.

Transverse waves.

Light travels much faster than sound. Due to this, the flash of gunshot is seen first and the sound of gunshot is heard a little later.

Transverse (water) waves.

Range of hearing in humans is 20Hz to 20,000Hz.

Pitch of a sound is directly proportional to frequency. Higher the frequency, higher is the pitch of the sound.

Transverse waves.