A tuning fork of frequency 512 ~Hz makes 4 beats/seconds with the vibrating string of a piano. The beat frequency decreases to 2 beats/s when the…
NEET UG 2010 — Physics Waves & Oscillations
2010mcqmedium
A tuning fork of frequency 512Hz makes 4 beats/seconds with the vibrating string of a piano. The beat frequency decreases to 2 beats/s when the tension in the piano string is slightly increased. The frequency of the piano string before increasing the tension was
Official previous-year question
Held on 30 Apr 2010 · Verified 9 Jul 2026.
Options
A
510Hz
B
514Hz
C
516Hz
D
508Hz
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Solution
Suppose np= frequency of piano = ? (np∝T)nf= frequency of tuning fork =512Hzx = Beat frequency =4 beats /s, which is decreasing (4→2) after changing the tension of piano wire. Also, tension of piano wire is increasing so np↑ Hence, np↑−nf=x↓⟶ wrong nf−np↑=x↓⟶ correjct ⇒np=nf−x=512−4=508Hz
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