CG Board Class 8 Science Sound Notes Textbook Exercises which includes Fill in the blanks, Question Answers and Extra Question and Answers from the Chapter.
Choose the correct answer out of the choices given–
- The range of audible frequencies for human beings is –
- (a) 0 – 20 Hertz
- (b) 20 – 2000 Hertz
- (c) 0 – 20,000 Hertz
- (d) 20 – 20,000 Hertz
- On increasing the frequency of a sound, what else increases –
- (a) Its pitch
- (b) Its intensity
- (c) Its time period
- (d) Its amplitude
- To hear the echo clearly, the minimum distance of the reflecting surface should be –
- (a) 11 metre
- (b) 34 metre
- (c) 17 metre
- (d) 50 metre
- Sound propagation is not possible –
- (a) In metals
- (b) In water
- (c) In vacuum
- (d) In air
Answer in 3-4 lines
Q: Write the definitions of amplitude and frequency.
Amplitude is the maximum displacement of an object from its mean position during oscillatory motion, indicating the strength or intensity of the vibration. Frequency is the number of oscillations or cycles of a vibrating object that occur in one second, measured in Hertz (Hz).
Q: Differentiate between a noise and a melodious sound.
A melodious sound is a pleasant sound created by harmonious vibrations, often made by musical instruments, while noise is an unpleasant, non-harmonious sound created by non-harmonious vibrations.
Q: Sound is heard clearly in a big room with curtains on its walls rather than in a room without curtains. Why?
In a room with curtain walls, sound is heard more clearly because curtains absorb sound waves and reduce their reflections and echoes. This absorption reduces the interference of sound waves, making it easier to hear the desired sounds in the room.