EXAMINATION PAPERS. 275
UNIVERSITY OF LONDON.
INTERMEDIATE MuS.B. EXAMINATION, 1895.
Morning, 10 to 1.
1. (a) How would you prove that the pitch of a note depends solely on the number of vibrations received per second by the hearer.
(b) And that the same number per second always gives the same note.
Ans. (a) In Savart's Toothed Wheel and in the Syren, as the speed increases or decreases, the pitch rises or falls, and nothing is altered except the number of vibrations received per second by the hearer.
(b) Tuning-forks vibrating the same number of times per second are found to give the same note. The same with other instruments.
2. (a) Describe and explain the mode of using a tonometer, consisting of a series of forks for the determination of frequency of vibration.
(i) For what reason are forks better than reeds in such a tonometer ? Ans. (a) See pp. 150 to 152. (*) See p. 151.
3. (a) How would you produce (1) transverse and (2) longtitudinal vibrations in a string; and (b) how would you in each case show that the vibrations were of the kind stated P
(e) How would you obtain the various harmonics ?
Ans. (a) (1) See p. 86. (2) See p. 118.
(b) By placing a rider on the string; or if the vibrations were very small, by viewing an illuminated point on the vibrating string with a low power miscroscope.
(e) (1) Seep. 92. (2) See p. 118.
4. A telegraph wire is 50 metres long, and is stretched with such a force that a transverse wave travels along it with velocity 125 metres per second, while a longitudinal wave travels with velocity 3,700 metres per second, (a) Find the frequency of the fundamental mode of vibration for each kind of vibration, (b) To what kind of vibration do you think it most likely that the sound heard at a telegraph pole belongs ? (e) Give a reason for your opinion, (d) How would you explain the beating often heard near the pole ?
Ans. (a) Transverse wave.
N = -^ (See p. 87.)
Therefore N = —— x — = li