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
Underline the verbs and arrange them in two columns, Past and Earlier past.
(a) My friends set out to see the caves in the next town, but I stayed at home, because I had seen them already.
(b) When they arrived at the station, their train had left. They came back home, but by that time I had gone out to see a movie!
(c) So they sat outside and ate the lunch I had packed for them.
(d) By the time I returned, they had fallen asleep!
Past Earlier Past - 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
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
- Match the organisms in Column A with their action in Column B.
A
B
(i) Bacteria (a) Fixing nitrogen (ii) Rhizobium (b) Setting of curd (iii) Lactobacillus (c) Baking of bread (iv) Yeast (d) Causing malaria (v) A protozoan (e) Causing cholera (vi) A virus (f) Causing AIDS (g) Producing antibodies - CBSE Class VIII
- Microorganisms
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
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.