Tiêu đề 16. Waves and Sound Med.pdf ✅

1. Which of the following waves is used in sonography? (a) Radiowaves (b) X-rays (c) Ultrasonic waves (d) Gamma rays 2. Which of the following waves does not travel in vaccum? (a) Seismic waves (b) X-rays (c) Light (d) Radio waves 3. Ultrasonic waves porduced by a vibrating quartz crystal are (a) Only longitudinal (b) Only transverse (c) Both longitudinal and transverse (d) Neither longitudinal nor transverse 4. Sound waves travel fastest in (a) Solids (b) Liquids (c) Gases (d) Vacuum 5. A transverse wave consists of (a) Only crests (b) Only throughs (c) Both crests and troughs (d) Rarefactions and compressions 6. A sound wave is a passing through air column in the form of compressions and rarefactions. In consecutive compressions and rarefactions, (a) Density remains constant (b) Boyle’s law is obeyed (c) Bulk modulus of air oscillates. (d) There is no transfer of heat. 7. In a transverse wave, the particles of the medium (a) Vibrate in a direciton perpendicular to the direction of the propagation. (b) Vibrate in a direction parallel to the direciton of the direciton othe propagation (c) Move in circle (d) Move in ellipse 8. The displacement of an elastic wave is given by the function y = 3 sin wt + 4 cos wt where y is in cm and t is in s. The resultant amplitude is (a) 3 cm (b) 4 cm (c) 5 cm (d) 7 cm 9. Figure shows a sinusoidal wave at a given instant. Which points are in phase? (a) A, B (b) B, C (c) B, D (d) C, E 10. Which of the following statements is incorrect during propagation of a plane progressive mechanical wave? (a) All the particles are vibrating in the same phase (b) Amplitude of all the particles is equal. (c) Particles of the medium executes SHM. (d) Wave velocity depends upon the nature of the medium. 11. The propagation constant of a wave is also called its (a) Wavelength (b) Frequency (c) Wave number (d) Angular wave number 12. Which of the following wave functions does not represent a travelling wave? (a) y = (x – vt)2 (b) y = log (x + vt) (c) y = x vt 1 + (d) All of these 13. The equation of a stationary wave along a stretched string is given by y = 5 sin x cos 40pt where x and y are in cm and t is in s. The separation between two adjacent nodes is (a) 1.5 cm (b) 3 cm (c) 6 cm (d) 4 cm 14. Two identical sinusoidal waves each of amplitude 10 mm with a phase difference of 120° are travelling in the same direction in a string. The amplitude of the resultant wave is (a) 5 mm (b) 10 mm (c) 15 mm (d) 20 mm 15. A student plotted the following four graphs representing the vatiation of velocity of sound in a gas with the pressure P. Which one is correct? (a) (b) (c) (d) 16. A body sends waves 100 mm long through medium A and 0.25 m long in medium B. If the velocity of waves in medium A is 80 cm s–1. The velocity of waves in medium B is (a) 1 m s–1 (b) 2 m s–1 (c) 3 m s–1 (d) 4 m s–1 17. The relation between frequency u, wavelength l and velocity of propagation of wave n is (a) v   = (b)  = v (c)   = v (d) None of these 18. Velocity of sound in vacuum is (a) Zero (b) 330 m s–1 (c) 360 m s–1 (d) 660 m s–1 19. At what temperature will the speed of sound in air be 3 times its value at 0°C? (a) 1184°C (b) 1148°C (c) 2184°C (d) 2148°C 20. Newton assumed that sound propagation in a gas takes under (a) Isothermal condition (b) Adiabatic condition (c) Isobaric condition (d) Isentropic condition 21. A hospital uses an ultrasonic scanner to locate tumours in a tissue. The operating frequency of the scanner is 3.2 MHz. The
speed of sound in a tissue is 1.6 km s–1. The wavelength of sound in the tissue is (a) 0.25 mm (b) 0.5 mm (c) 0.75 mm (d) 1 mm 22. A 10 m long steel wire has mass 5 g. If the wire is under a tension of 80 N, the speed of transverse waves on the wire is (a) 100 m s–1 (b) 200 m s–1 (c) 400 m s–1 (d) 500 m s–1 23. According to Newton’s formula, the speed of sound in air at STP is (Take the mass of 1 mole of air is 29 × 10–3 kg) (a) 250 m s–1 (b) 260 m s–1 (c) 270 m s–1 (d) 280 m s–1 24. A progressive wave is represented by y = 5 sin (100  t – 2  x) where x and y are in m and t is in s. The maximum particle velocity is (a) 100  m s–1 (b) 200  m s–1 (c) 400  m s–1 (d) 500  m s–1 25. If nrms is the rms speed of molecules in a gas and n is the speed of sound waves in the gas, then the ratio is (a)  3 (b) 3  (c) 3 (d)  3 26. The speed of transverse wave on a stretched string is (a) Directly proportional to the tension in the string (b) Directly proportional to the square root of the tension (c) Inversely proportional to tension (d) Inversely proportional to square root of tension 27. A sound is produced by plucking a string in a musical instrument, then (a) The velocity of wave in the string is equal to the velocity of sound in the string (b) The frequency of the wave in the string is equal to the frequency of the sound produced (c) The wave in the string is progressive (d) The tension in the string varies from point to point 28. Speed of sound waves in a fluid is (a) Directly proportional to the square root of bulk modulus of the medium (b) Inversely proportional to the bulk modulus of the medium (c) Directly proportional to the density of the medium (d) Inversely proportional to the density of the medium 29. Figure given shows a sinusoidal wave on a string. If the frequency of the wave is 150 Hz, what is the velocity and wavelength of the given wave? (a) 0.04 m, 10 m s–1 (b) 0.06 m, 12 m s–1 (c) 0.08 m, 10 m s–1 (d) 0.08 m, 12 m s–1 30. If the bulk modulus of water is 2100 MPa, what is the speed of in water? (a) 1450 m s–1 (b) 2100 m s–1 (c) 1400 m s–1 (d) 1200 m s–1 31. A transverse harmonic wave on a string is described by y(x, t) = 3 sin        + + 4 36t 0.018x where x and y are in cm and t is in s. Which of the following statements is incorrect? (a) The wave is travelling in negative x-direction (b) The amplitude of the wave is 3 cm. (c) The speed of the wave is 20 m s–1 (d) The frequency of the wave is  9 Hz. 32. An earthquake generates both transverse (S) and longitudinal (P) sound waves in teh earth. The speed of S waves is about 4 km s–1 and that of P waves is about 8 km s–1. A seismograph records P and S waves from an earthquake. The first P wave arrives 4 min before the first S wave. The epicentre of the earthquake is located at a distance of about (a) 192 km (b) 384 km (c) 1920 km (d) 3840 km 33. The ratio of the velocity of sound in hydrogen        = 5 7 to that in helium        = 3 5 at the same temperature is (a) 42 5 (b) 21 5 (c) 5 42 (d) 5 21 34. A tuning fork A of frequency 512 Hz produces 5 beats per second when sounded with another tuning fork B of unknown frequency. IfB is loaded with wax the number of beats is again 5 per second. The frequency of the tuning fork B before it was loaded is (a) 502 Hz (b) 507 Hz (c) 517 Hz (d) 522 Hz 35. Which of the following properties of a wave is independent of others? (a) Velocity (b) Frequency (c) Amplitude (d) Wavelength 36. A transverse wave is represented by y = Asin(  t – kx). For waht value of the wavelength is the wave velocity equal to the maximum particle velocity? (a) 2 A (b) A (c) 2  A (d) A 37. Sound waves travel at 350 m s–1 through a warm air and at 3500 m s–1 through brass. The wavelength of a 700 Hz acoustic wave as it enters brass from warm air (a) Decrease by a factor 10 (b) Increase by a factor 20 (c) Increase by a factor 10 (d) Decrease by a factor 20
38. A man standing between two parallel hills, claps his hand and hears successive echoes at regular intervals of 1 s. If velocity of sound is 340 m s–1, then the distance between the hills is (a) 100 m (b) 170 m (c) 510 m (d) 340 m 39. The stationary wave y = 2a sin kx cos wt in a stretched string is the result of superposition of y1 = a sin (kx – wt) and (a) y2 = a cos (kx +  t) (b) y2 = a sin (kx +  t) (c) y2 = a cos (kx –  t) (d) y2 = a sin (kx –  t) 40. A steel rod of length 100 cm is clamped at the middle. The frequency of the fundamental mode for the longitudinal vibrations of the rod is (speed of sound in steel = 5 km s–1) (a) 1.5 kHz (b) 2 kHz (c) 2.5 kHz (d) 3 kHz 41. When sound wave is refracted from air to water which of the following quantities remians unchanged? (a) Wavelength (b) Wave number (c) Wave velocity (d) Frequency 42. A pipe 30 cm long, is open at both ends. Which harmonic mode of the pipe resonates a 1.1 kHz source? (speed of sound in air = 330 m s–1) (a) First (b) Second (c) Third (d) Fourth 43. A bat emits ultrasonic sound of frequency 100 kHz in air. If this sound meets a water surface, the wavelengths of the reflected and transmitted sound are (speed of sound in air 340 m s–1 and in water = 1500 ms–1) (a) 3.4 mm, 30 mm (b) 6.8 mm, 15 mm (c) 3.4 mm, 15 mm (d) 6.8 mm, 30 mm 44. The phenomenon of echo is an example of (a) Reflection (b) Refraction (c) Beat (d) Resonance 45. Which of the following statements is incorrect for a stationary wave? (a) Every particle has fixed amplitude which is different from the amplitude of its nearest particle (b) All the particles cross their eman position at the same time (c) All the particles are oscillating with same amplitude (d) There is no net transfer of energy across any plane. 46. When a string fixed at its both ends vibrates in 1 loop, 2 loops, 3 loops and 4 loops, the frequencies are in the ratio (a) 1 : 1 : 1 : 1 (b) 1 : 2 : 3 : 4 (c) 4 : 3 : 2 : 1 (d) 1 : 4 : 9 : 16 47. A pipe 17 cm long is closed at one end. Which harmonic mode of the pipe resonates a 1.5 kHz source? (speed of sound in air = 340 m s–1) (a) First (b) Third (c) Fifth (d) Seventh 48. A resonating air column shows resonance with a tuning fork of frequency 256 Hz at column lengths 33.4 cm and 101.8 cm. The speed of sound in air is (a) 300 m s–1 (b) 250 m s–1 (c) 390 m s–1 (d) 350 m s–1 49. In stationary waves, nodes are the points where there is (a) Minimum displacement and minimum pressure change (b) Minimum displacement and maximum pressure change (c) Maximum displacement and maximum pressure change (d) Maximum displacement and minimum pressure change 50. Which of the following statements is correct? (a) The distance between any two consecutive antinodes or nodes is 4  (b) The distance between a node and adjoining antinode is 4  (c) In the open end is an node (d) In the closed end is an antinode 51. In an organ pipe of length L open at both ends, the fundamental mode has a frequency (where v is a speed of sound in air) (a) 2L v and only odd harmonics are present. (b) 2L v and only even harmonics are present (c) 2L v and all harmonics are present (d) 4L v and only odd harmonics are present. 52. A tunning fork of frequency 440 Hz resonates wit a tube closed at one end of length 1.8 cm and diameter 5 cm in fundamental mode. The vleocity of sound in air is (a) 336 m s–1 (b)343 m s–1 (c) 300 m s–1 (d) 350 m s–1 53. A pulse of wave train travels along a stretched string and reaches the fixed end of the string it will be reflectexd back with (a) A phase change of 180° with velocity reversed. (b) The same phase as the incident pulse with no reversal of velocity (c) A phase change of 180° with no reversal of velocity (d) The same phase as the incident pulse but with velocity reversed. 54. A string fixed at its both ends vibrates in 5 loops as shown in the figure The total number of nodes and antinodes are respectively. (a) 5, 6 (b) 6, 5 (c) 7, 4 (d) 4, 7 55. The fundamental note produced by a closed organ pipe is of frequncy  The fundamental note produced by an open organ pipe of same length will be of frequency (a) 2  (b)  (c) 2  (d) 4 