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Q14.7: NCERT Physics - Part 2 WAVES 14.7 Solution: A hospital uses an ultrasonic scanner to locate tumours in a…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students often plug $v=1.7$ directly into $lambda=v/f$ while using $f=4.2\times10^6\,$Hz, forgetting to convert km s⁻¹ to m s⁻¹; this yields a wavelength 1000× too large. Always change the speed to metres per second before dividing by the frequency.

A hospital uses an ultrasonic scanner to locate tumours in a tissue. What is the wavelength of sound in the tissue in which the speed of sound is 1.7 km s__? The operating frequency of the scanner is 4.2 MHz.

Step-by-Step Verified Solution

**Answer:** λ=4.05×10−4 m\lambda = 4.05 \times 10^{-4} \text{ m} **Step-by-Step Explanation:** Given: v=1.7v = 1.7 km/s =1700= 1700 m/s, f=4.2f = 4.2 MHz =4.2×106= 4.2 \times 10^6 Hz.
λ=vf=17004.2×106=4.05×10−4 m\lambda = \frac{v}{f} = \frac{1700}{4.2 \times 10^6} = 4.05 \times 10^{-4} \text{ m}

All Questions in this Chapter

Q14.1 Q14.2 Q14.3 Q14.4 Q14.5 Q14.6 Q14.7 Q14.8 Q14.9 Q14.10 Q14.11 Q14.12 Q14.13 Q14.14 Q14.15 Q14.16 Q14.17 Q14.18 Q14.19

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