AIIMS 2019 Physics Sound Waves MCQ Question

In an open organ pipe, the fundamental frequency (first harmonic) is given by the formula $f = \frac{v}{2L}$, where $v$ is the speed of sound and $L$ is the length of the pipe. For a pipe of length 1 m and speed of sound at 330 m/s, the fundamental frequency is $f = \frac{330}{2 \times 1} = 165$ Hz. The harmonics are integer multiples of the fundamental frequency, so the frequencies are 165 Hz, 330 Hz, 495 Hz, and 660 Hz, all of which are ≤ 1000 Hz. However, the next harmonic (825 Hz) and beyond exceed the limit of 1000 Hz, meaning only 4 harmonics fit within the criteria, but since the question asks for tones, which typically refers to distinct frequencies, the answer is effectively none of the provided options, leading to option D being correct. Other options are incorrect as they miscount the harmonics or tones based on the given frequency limit.