Which one of the following statements is not true for a flute, a musical instrument?
- (a)Momentum of waves on the blowing jet determines the loudness of the produced note.
- (b)Arrival time of the waves on the blowing jet determines the pitch of the produced note.
- (c)Sound comes from a vibrating column of air inside the flute.
- (d)Sound comes from a vibrating column of air inside as well as outside the flute.
Correct — D is the statement that is not true. A flute is essentially an open pipe: its note is produced by a standing wave in the column of air enclosed inside the tube. There is no vibrating air column 'outside' the flute generating the sound, so saying the sound comes from a column of air inside as well as outside is false. Statement C correctly locates the sound source (the internal air column), which is exactly what D wrongly extends.
- (a)Momentum of waves on the blowing jet determines the loudness of the produced note. — This is true — how hard the player blows (the energy and momentum carried by the air jet) sets the amplitude, and hence the loudness, of the note; so it is not the false statement.
- (b)Arrival time of the waves on the blowing jet determines the pitch of the produced note. — This is true — the timing (and hence frequency) with which the oscillating air jet feeds the pipe locks to the resonant frequency of the air column, fixing the pitch; so it is not the exception.
- (c)Sound comes from a vibrating column of air inside the flute. — This is true — the flute's tone is the standing wave of the air column inside the tube; being a correct statement, it is not the answer to a 'not true' question.
A flute is a wind instrument that behaves like an open organ pipe. Blowing across the embouchure hole sets up an oscillating air jet at the edge; this drives a standing wave in the air column inside the tube, which is the sound. Opening and closing finger holes changes the effective length of that internal column and so changes the pitch. Loudness depends on how energetically the jet is blown.
Statements C and D are near-duplicates: both credit the internal air column, but D tacks on 'as well as outside'. That extra clause is the error — the resonating, sound-producing column is inside the pipe, not outside. Recognising that the flute is an air-column (open-pipe) instrument settles it.
- A flute acts as an open pipe; sound is a standing wave of the air column inside the tube.
- Finger holes alter the effective length of the internal air column, changing the pitch.
- Pitch is set by the resonant frequency of that column; loudness by how hard one blows.
- The driving mechanism is an air jet oscillating at the edge (embouchure) of the mouth hole.
- Overlooking the small added phrase 'as well as outside' that turns a true statement (c) into a false one (d).
- Confusing loudness (amplitude, set by blowing energy) with pitch (frequency, set by the air-column length).
Asked as a 'which statement is NOT true' conceptual item on how a wind instrument produces sound.
No directly related past PYQ was found.
- practice — not a real PYQ
The pitch of the note from a flute is changed mainly by:
- (a)blowing harder
- (b)changing the effective length of the air column with finger holes
- (c)warming the flute
- (d)holding the flute higher
Answer(b) changing the effective length of the air column with finger holes.
- practice — not a real PYQ
A flute produces sound as a result of vibrations of:
- (a)a stretched string
- (b)a metal reed
- (c)the column of air inside it
- (d)a tight membrane
Answer(c) the column of air inside it — it is an open-pipe instrument.