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Q9
(NDA-I/2015)
Science & Technology › Basic Science (Physics, Chemistry, Biology) › Waves and acoustics
Answer Verified
Ultrasonic waves of frequency 3 * 105 Hz are passed through a medium where speed of sound is 10 times that in air (Speed of sound in air is 300 m/s). The wavelength of this wave in that medium will be of the order of
Result
Your answer:
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Correct:
A
Explanation
To find the wavelength of the ultrasonic wave, we use the fundamental wave relationship v = fλ, where v is the speed, f is the frequency, and λ is the wavelength. The problem states the frequency (f) is 3 * 10^5 Hz. The speed of sound in the medium is 10 times the speed in air (300 m/s), resulting in a medium speed (v) of 3000 m/s. Rearranging the formula to λ = v / f, we calculate λ = 3000 / (3 * 10^5). This simplifies to 1000 / 10^5, which equals 10^-2 meters. Since 10^-2 meters is exactly 1 cm, the wavelength of the wave in this specific medium is of the order of 1 cm. This calculation aligns with the standard physical definitions of wavelength and frequency relationships for mechanical waves [1].
Sources
- [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 15: Tsunami > Basics > p. 192
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