Class 9 Science
Question 1: Note is a sound
Answer: (a) of mixture of several frequencies
Question 2: A key of a mechanical piano struck gently and then struck again but much harder this time. In the second case
Answer: (d) both loudness and pitch will remain unaffected
Question 3: In SONAR, we use
Answer: (a) Ultrasonic waves
Question 4: Sound travels in air if
Answer: (c) Disturbance moves
Question 5: When we change feeble sound to loud sound we increase its
Answer: (b) Amplitude
Question 6: In the curve (Figure) half the wavelength is
Answer: (a) AB
Question 7: Earthquake produces which kind of sound before the main shock wave begins
Answer: (b) Infrasound
Question 8: Infrasound can be heard by
Answer: (c) Rhinoceros
Question 9: Before playing the orchestra in a musical concert, a sitarist tries to adjust the tension and pluck the string suitably. By doing so, he is adjusting
Answer: (c) Frequency of the sitar string with the frequency of other musical instruments
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