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
- In the tsunami 150,000 people died. How many animals died?
- CBSE Class VIII
- The Tsunami
- Subtract 4p2q – 3pq + 5pq2 – 8p + 7q – 10 from 18 – 3p – 11q + 5pq – 2pq2 + 5p2q
- CBSE Class VIII
- Addition and Subtraction of Algebraic Expressions
Say whether the following are true or false.
1. Ignesious lost his wife, two children, his father-in-law, and his brother-in-law in the tsunami.
2. Sanjeev made it to safety after the tsunami.
3. Meghna was saved by a relief helicopter.
4. Almas’s father realised that a tsunami was going to hit the island.
5. Her mother and aunts were washed away with the tree that they were holding on to.
- CBSE Class VIII
- The Tsunami
- Find the product.
(i) (5 – 2x) (3 + x)
(ii) (x + 7y) (7x – y)
(iii) (a2+ b) (a + b2)
(iv) (p2 – q2) (2p + q)- CBSE Class VIII
- Multiplying a Polynomial by a Polynomial
Name these people.
(i) The ruler who fought pitched battles against the British and died fighting.
(ii) The person who wanted to reform the society.
(iii) The person who recommended the introduction of English education in India.
(iv) Two popular leaders who led the revolt (Choices may vary.)
- CBSE Class VIII
- Glimpses of the past
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.