Identify the part which vibrates to produce sound in the following instruments.- Dholak
- Sitar
- Flute
- Dholak
- Sitar
- Flute
Approach Solution - 1
(a) Dholak: Dholak has stretched membranes which vibrate to produce sound.
(b) Sitar: In sitar, the stretched strings, when vibrate, they produce sound.
(c) Flute: Flute is a wind musical instrument which uses air column to produce sound.
Approach Solution -2
(b) The parts that vibrate in a sitar are stretched strings.
(c) The part that vibrates in a flute is the air column inside it.
Questions Asked in CBSE Class VIII exam
Fill in the blanks using the correct form of the verbs in brackets.
My little sister is very naughty. When she ____ (come) back from school yesterday, she had _____(tear) her dress. We _____(ask) her how it had _____(happen). She ______(say) she _____ _____ (have, quarrel) with a boy. She _____ _____ (have, beat) him in a race and he _____ ____ (have, try) to push her. She _____ ____ (have, tell) the teacher and so he _____ _____ (have, chase) her, and she _____ _____ (have, fall) down and _____ _____ (have, tear) her dress.
- CBSE Class VIII
- The Best Christmas Present in the world
- Subtract 4p2q – 3pq + 5pq2 – 8p + 7q – 10 from 18 – 3p – 11q + 5pq – 2pq2 + 5p2q
- CBSE Class VIII
- Addition and Subtraction of Algebraic Expressions
- The process that you saw in Activity 11.7 is used for purification of copper. A thin plate of pure copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is sought to be transfered to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?
- CBSE Class VIII
- Electroplating
- Explain why a charged balloon is repelled by another charged balloon whereas an uncharged balloon is attracted by another charged balloon?
- CBSE Class VIII
- Types of Charges and Their Interaction
- Write a paragraph in your own words on each of the following.
1. Preparation of soil
2. Sowing
3. Weeding
4. Threshing- CBSE Class VIII
- Basic Practices of Crop Production
Concepts Used:
Sound
Sound is a vibration that propagates the mechanical wave of displacement and pressure, through a medium can be of any matter. In other words, the sound is the thin line between Music sound and Noise.
Types of Sounds:
Sound can be divided into two types depending on its frequency. The following are:-
Infrasonic Waves:
- Infrasonic waves have a frequency lower than 20 Hz. Since it is below the human hearing range, it is inaudible to humans.
- However, several other living organisms use these waves to communicate, whales, sharks, elephants, hippopotamus, etc. these waves are also used in the scientific field, it is used to study upcoming earthquakes, volcanic eruptions, human heart rates, rock formation stages, etc.
Ultrasonic waves:
- Ultrasonic waves have a frequency higher than 20 kHz. Since it is above the human hearing range, it is inaudible to humans.
- These waves are used in the scientific field, it is used to study human heart rates, to take sonograms, navigation of directions, imaging things, uniform sample mixing, communication, testing of samples, etc.