For the sound wave represented by the graph shown in Fig., what is half of its wavelength? Class 9

For the sound wave represented by the graph shown in Fig., what is half of its wavelength? Class 9

Question 1.

For the sound wave represented by the graph shown in Fig., what is half of its wavelength? (Page 195) Class 9

Answer:

From the above given Fig., the x-axis shows distance up to 4.5 cm with markings at 1.5 and 3.0 cm. One complete wave (crest to crest or trough to trough) spans 3.0 cm, so the wavelength λ = 3.0 cm. Half of wavelength - 3.0/2 = 1.5 cm

Question 2.

Given Table shows the speed of sound in a few media at atmospheric pressure. (Page 197) Class 9

Compare the speeds by finding the ratio of:

(i) the speed of sound in water with respect to the speed in the air.

(ii) the speed of sound in steel with respect to the speed in the water.

Answer:

(i) Speed in water / Speed in air = 1500 / 340 ≈ 4.41 (approximately 4.4 times)

(ii) Speed in steel / Speed in water = 5000 /1500 ≈ 3.33 (approximately 3.3 times)