Ans. The bat produces high pitched ultrasonic waves. The waves on striking the insect return back, which is heard by the bat. On hearing the echo the bat locates the insect and catches it.
Q.2.How does the stethoscope help the doctors in listening to the sound of the patients heart beat?
Ans. In a stethoscope, the sound produced within the body of a patient is picked up by a sensitive diaphragm and then reaches the doctor's ear by multiple reflections.
Q.3. Explain how defects in a metal block can be detected using ultrasound.
Ans. To detect minor cracks or flaws in metal block, ultrasonic waves are allowed to pass through metal blocks and detectors are used to detect the transmitted waves. If there is a crack in metal block, these waves get reflected back
Q.4. How is ultrasound used for cleaning?
Ans. The object to be cleaned is put in a tank fitted with ultrasonic vibrator. The tank is filled with cleaning solution. As the ultrasonic vibrator is switched on, high frequency vibrations are set up and the dust, grease and dust particles get detached and the object gets thoroughly cleaned.
Q.5. What is echo ranging? State any one application of this technique.
Solutions for Class 9th Science: Chapter 12 Sound
CBSE NCERT IX-Physics for term-II Chapter: Sound key points
Read Full Post