The Science Inn Academy Larkano sounded with a tuning fork of frequency

100 produces one beat, then the

frequency of the other tuning fork is…
Beats (a) 102 (b) 98 (c) 99 (d) 101
03342015628 5. A tuning fork sounded together with a
tuning fork of frequency 256 emits two
By Faisal Wadho beats. On loading the tuning fork of
frequency 256, the number of beats heard
1. Two tuning forks when sounded together are 1 per second. The frequency tuning
produced 4 beats/sec. The frequency of fork is…
one fork is 256. The number of beats (a) 257 (b) 258 (c) 256 (d) 254
heard increases when the fork of 6. If two tuning forks A and B are sounded
frequency 256 is loaded with wax. The together, they produce 4 beats per second.
frequency of the other fork is… A is then slightly loaded with wax, they
(a) 504 (b) 520 (c) 260 (d) 252 produce 2 beats when sounded again. The
2. Beats are the result of… frequency of A is 256. The frequency of
(a) Diffraction B will be….
(b) Destructive interference (a) 250 (b) 252 (c) 260 (d) 262
(c) Constructive and destructive 7. The frequencies of two sound sources are
interference 256Hz and 260 Hz. At 𝑡 = 0 , the
(d) Superposition of two waves of nearly intensity of sound is maximum. Then the
equal frequency phase difference at the time 𝑡 = 1/16 sec
3. Two adjacent piano keys are struck will be…
simultaneously. The notes emitted by (a) Zero (b) 𝑝 (c) 𝑝/2 (d) 𝑝/4
them have frequencies 𝑛1 and 𝑛2 . The 8. Two tuning forks have frequencies 450
number of beats heard per second is… Hz and 454 Hz respectively. On sounding
1 1
(a) (𝑛1 − 𝑛2 ) (b) (𝑛1 + 𝑛2 ) these forks together, the time interval
2 2
between successive intensities will be…
(c) (𝑛1 − 𝑛2 ) (d) 2(𝑛1 − 𝑛2 ) (a) 1/4 s (b) 1/2 s (c) 1 s (d) 2 s
9. When a tuning fork of frequency 341 is
4. A tuning fork of frequency 100 when
sounded with another tuning fork, six
sounded together with another tuning fork
beats per second are heard. When the
of unknown frequency produces 2 beats
second tuning fork is loaded with wax
per second. On loading the tuning fork
and sounded with the first tuning fork, the
whose frequency is not known and
number of beats is two per second. The
 natural frequency of the second tuning one arm of A is filed, then the number of
fork is… beats increases. Frequency of A will be…
(a) 334 (b) 339 (c) 343 (d) 347 (a) 502 (b) 507 (c) 517 (d) 522
10. Two tuning forks of frequencies 256 and 15. The beats are produced by two sound
258 vibrations/sec are sounded together, sources of same amplitude and of nearly
then time interval between consecutive equal frequencies. The maximum
maxima heard by the observer is… intensity of beats will be ….that of one
(a) 2 s (b) 0.5 s (c) 250 s (d) 252 s source.
11. A tuning fork gives 5 beats with another (a) Same (b) Double (c) Four times
tuning fork of frequency 100 Hz. When (d) Eight times
the first tuning fork is loaded with wax, 16. Beats are produced by two waves given
then the number of beats remains by 𝑦1 = 𝑎 sin 2000𝜋𝑡 and 𝑦2 =
unchanged, then what will be the 𝑎 sin 2008𝜋𝑡. The number of beats heard
frequency of the first tuning fork…. per second is…
(a) 95Hz (b) 100Hz (c) 105Hz (d) 110Hz (a) Zero (b) One (c) Four (d) Eight
12. Tuning fork 𝐹1 has a frequency of 256 17. A tuning fork whose frequency as given
Hz and it is observed to produce 6 beats/s by manufacturer is 512 Hz is being tested
with another tuning fork 𝐹2 . When 𝐹2 is with an accurate oscillator. It is found
loaded with wax, it still produces 6 that the fork produces a beat of 2Hz when
beats/s with 𝐹1 . The frequency of 𝐹2 oscillator reads 514 Hz but produces a
before loading was… beat of 6 Hz when oscillator reads 510
(a) 253Hz (b) 262Hz (c) 250Hz (d)259Hz Hz. The actual frequency of fork is…
13. A tuning fork and a Sonometer wire (a) 508 Hz (b) 512Hz
were sounded together and produces 4
(c) 516 Hz (d) 518 Hz
beats/s. When the length of sonometer
wire is 95 cm or 100 cm, the frequency of 18. A tuning fork of frequency 480 Hz
the tuninf fork is… produces 10 beats per second when
(a) 156 Hz (b) 152 Hz sounded with a vibrating sonometer
string. What must have been the
(c) 148 Hz (d) 160 Hz
frequency of the string if a slight increase
14. Two tuning forks A and B vibrating in tension produces lesser beats per
simultaneously produce 5 beats. second than before…
Frequency of B is 512. It is seen that if (a) 460 Hz (b) 470 Hz

(c) 480 Hz (d) 490 Hz

19. When a tuning fork A of unknown 23. A tuning fork A of frequency 200 Hz is
frequency is sounded with another tuning sounded with fork B, the number of beats
fork B of frequency 256 Hz, then 3 beats per second is 5. By putting some wax on
per second are observed. After that A is A, the number of beats increases to 8.
loaded with wax and sounded, the again 3 The frequency of fork B is…
beats per second are observed. The (a) 200 Hz (b) 195 Hz
frequency of the tuning fork A is…
(c) 192 Hz (d) 205 Hz
(a) 250 Hz (b) 253 Hz
24. Two tuning forks, A and B, give 4 beats
(c) 259 Hz (d) 262 Hz
per second when sounded together. The
20. A source of sound gives five beats per frequency of A is 320 Hz. When some
second when sounded with another wax is added to B and it is sounded with
source of frequency 100𝑠 −1. The second A, 4 beats per second are again heard.
harmonic source of the source together The frequency of B is…
with a source of frequency 205 𝑠 −1, gives (a) 312 Hz (b) 316 Hz
five beats per second. What is the
(c) 324 Hz (d) 328 Hz
frequency of the source?
(a) 105 𝑠 −1 (b) 205 𝑠 −1 25. Two tuning forks have frequencies 380
and 384 Hz respectively. When they are
(c) 95 𝑠 −1 (d) 100 𝑠 −1
sounded together, they produce 4 beats,
21. When two sound waves are After hearing the maximum sound, how
superimposed, beats are produced when long will it take to hear the minimum
they have… sound….
(a) Different amplitudes and phases (a) 1/2 s (b) 1/4 s
(b) Different velocities
(c) 1/8 s (d) 1/16 s
(c) Different phases
(d) Different frequencies 26. Beats are produced with the help of two
22. Two tuning fork A and B give 4 beats sound waves of amplitudes 3 and 5 units.
per second. The frequency of A is 256 The ratio of maximum to minimum
Hz. On loading B slightly, we get 5 beats intensity in the beats is….
in 2 seconds. The frequency of B after (a) 2:1 (b) 5:3 (c) 4 :1 (d) 16 :1
loading is … 27. Two waves of lengths 50 cm and 51 cm
(a) 253.5 Hz (b) 258.5 Hz produced 12 beats per second. The
velocity of sound is…
(c) 260 Hz (d) 252 HZ
 (a) 306 m/s (b) 331 m/s (a) 10 (b) 4 (c) 20 (d) 6
34. Two sound waves of slightly different
(c) 340 m/s (d) 360 m/s
frequencies propagating in the same
28. Two waves 𝑦 = 0.25 sin 316𝑡 and 𝑦 = direction produce beats due to…
0.25 sin 310𝑡 are travelling in same (a) Interference
direction. The number of beats produced (b) Diffraction
per second will be…. (c) Polarization
(a) 6 (b) 3 (c) 3/p (d) 3 p (d) Refraction
29. The couple of tuning forks produces 2 35. On sounding tuning fork A with another
beats in the time interval of 0.4 seconds. tuning fork B of frequency 384 Hz, 6
so the beat frequency is… beats are produced per second. After
(a) 8 Hz (b) 5 Hz loading the prongs of A with some wax
and then sounding it again with B, 4 beats
(c) 2 Hz (d) 10 Hz are produced per second. What is the
30. An unknown frequency x produces 8 frequency of the tuning fork A…
beats per seconds with a frequency of (a) 388 Hz (b) 380 Hz
250Hz and 12 beats with 270 Hz source, (c) 378 Hz (d) 390 Hz
then x is….
(a) 258 Hz (b) 242 Hz 36. It is possible to hear beats from the two
vibrating sources of frequency…
(c) 262 Hz (d) 282 Hz (a) 100 Hz and 150 Hz
31. Beats are produced by two waves 𝑦1 = (b) 20 Hz and 25 Hz
𝑎 sin 1000𝜋𝑡 , 𝑦2 = 𝑎 sin 998𝜋𝑡 . The (c) 400 Hz and 500 Hz
number of beats heard/sec is… (d) 1000 Hz and 1500 Hz
(a) 0 (b) 2 (c) 1 (d) 4 37. A tuning fork gives 4 beats with 50 cm
32. The wavelength of two waves are 50 and length of a sonometer wire. If the length
51 cm respectively. If the temperature of of the wire is shortened by 1 cm, the
the room is 200 𝐶, then what will be the number of beats is still the same. The
number of beats produced per second by frequency of the fork is…
these waves, when the speed of sound at (a) 396 (b) 400 (c) 404 (d) 384
00 𝐶 332 m/s …. 38. Two sound waves of wavelengths 5m
(a) 14 (b) 10 (c) 24 (d) N.O.T and 6 m formed 30 beats in 3 seconds.
33. Maximum number of beats frequency The velocity of sound is…
heard by a human being is… (a) 300 𝑚𝑠 −1 (b) 310 𝑚𝑠 −1
 (c) 320 𝑚𝑠 −1 (d) 330 𝑚𝑠 −1 (c) 256− 2 Hz
(d) 256− 5Hz
39. The wavelength of a particle is 99 cm
44. When temperature increases, the
and that of other is 100 cm. Speed of
frequency of a tuning fork….
sound is 396 m/s. The number of beats
(a) Increases (b) Decreases
heard is…
(a) 4 (b) 5 (c) 1 (d) 8 (c) Remains same (d) Increases or
40. A tuning fork arrangement (pair) Decreases depending on the material
produces 4beats/s with one fork of
45. Two strings X and Y of a sitar produce a
frequency 288 cps. A little wax is placed
beat frequency 4 Hz. When the tension of
on the unknown fork and it then produces
the string Y is slightly increased the beat
2beats/s. The frequency of the unknown
frequency is found to be 2 Hz. If the
fork is…
frequency of X is 300 Hz, then the
(a) 286 cps (b) 292 cps (c) 294 cps (d)
original frequency of Y was….
288 cps
(a) 296 Hz (b) 298 Hz
41. A tuning fork vibrates with 2beats in
0.04second. The frequency of the fork (c) 302 Hz (d) 304 Hz
is…
(a) 50 Hz (b) 100 Hz (c) 80 Hz (d) 46. The frequency of tuning forks A and B
none are respectively 3% more and 2% less
42. Two sound sources when sounded than the frequency of tuning fork C. when
simultaneously produce four beats in A and B are simultaneously excited, 5
beats per second are produced. Then the
0.25second. The difference in their
frequencies must be…. frequency of the tuning fork A (in Hz)
(a) 4 (b) 8 (c) 16 (d) 1 is…
43. A tuning fork of known frequency 256 (a) 98 (b) 100 (c) 103 (d) 105
Hz makes 5 beats per second with the 47. When a tuning fork vibrates, the waves
vibrating string of a piano. The beat produced in the fork are….
(a) Longitudinal
frequency decreases to 2 beats per second
(b) Transverse
when the tension in the piano string is
(c) Progressive
slightly increased. The frequency of the
piano string before increasing the tension (d) Stationary
was… 48. Two vibrating tuning forks produce
(a) 256 + 5 Hz progressive waves given by 𝑦1 =
(b) 256 + 2 Hz 4 sin 500𝜋𝑡 , and 𝑦2 = 2 sin 506𝜋𝑡 ,
 Number of beats produced per minute
is…
(a) 360 (b) 180 (c) 3 (d) 60
49. When a tuning fork produces sound
waves in air, which one of the following
is same in the material of tuning fork as
well as in air…
(a) Wavelength (b) Frequency

(c) Velocity (d) Amplitude

50. The disc of a siren containing 60holes

rotates at a constant speed 460 rpm. The
emitted sound is in unison with a tuning
fork of frequency….
(a) 10 Hz (b) 360 Hz

(c) 216 Hz (d) 6 Hz

 Answer Key OF BEATS TEST MSCQs
1. C 11. C 21. D 31. C 41. A
2. D 12. B 22. C 32. A 42. C
3. C 13. A 23. D 33. A 43. D
4. A 14. C 24. C 34. A 44. B
5. D 15. C 25. C 35. D 45. A
6. B 16. C 26. D 36. B 46. C
7. C 17. C 27. A 37. A 47. A
8. A 18. B 28. C 38. A 48. B
9. D 19. C 29. B 39 A 49. B
10 B 20. A 30. A 40. B 50. B