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NEET PHYSICSWAVEEasy

Question

Sound waves travel at 350 m/s350 \text{ m/s} through warm air and at 3500 m/s3500 \text{ m/s} through brass. The wavelength of a 700 Hz700 \text{ Hz} acoustic wave as it enters brass from warm air:

A

increases by factor 20

B

increases by factor 10

C

decreases by factor 20

D

decreases by factor 10

Step-by-Step Solution

  1. Identify the Constant Property: When a wave passes from one medium to another (e.g., from air to brass), its frequency (ff) remains constant.
  2. Relate Wavelength and Speed: The speed of a wave is given by the formula v=fλv = f\lambda. Since the frequency ff is constant, the wavelength λ\lambda is directly proportional to the wave speed vv (i.e., λv\lambda \propto v).
  3. Calculate the Ratio: We can find the change in wavelength by taking the ratio of the speeds in the two media: λbrassλair=vbrassvair\frac{\lambda_{\text{brass}}}{\lambda_{\text{air}}} = \frac{v_{\text{brass}}}{v_{\text{air}}} λbrassλair=3500 m/s350 m/s=10\frac{\lambda_{\text{brass}}}{\lambda_{\text{air}}} = \frac{3500 \text{ m/s}}{350 \text{ m/s}} = 10
  4. Conclusion: The wavelength in brass is 10 times the wavelength in air. Therefore, the wavelength increases by a factor of 10.

Exam Context & Concepts Covered

This question aligns with the NEET PHYSICS syllabus, specifically targeting concepts from WAVE. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

PHYSICSWAVEtravelthroughthroughwavelengthacoustic

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