Waves Questions and Answers

Three waves producing displacement in the same direction of same frequency and of amplitudes 10 m 4 m and 7 m arrive at a point with successive phase difference of 2 The amplitude of the resultant wave is Question Type Single Correct Type 12 m 2 7 m 3 5 m

12 A taut string at both ends vibrates in its nth overtone The distance between adjacent Node and Antinode is found to be d If the length of the string is L then a L 2d n 1 c L 2dn b L d n 1 d L 2d n 1

A vibrating string of certain length under a tension T resonates with a mode corresponding to the first overtone third harmonic of an air column of length 75 cm inside a tube closed at one end The string also generates 4 beats per second when excited along with a tuning fork of frequency n Now when the tension of the string is slightly increased the number of beats reduces to 2 per second Assuming the velocity of sound in air to be 340 m s the frequency n of the tuning fork in Hz is A 344 B 336 C 117 3 D 109 3

Out of the given four waves 1 2 3 and 4 y asin kx of 1 y a sin t kx 2 y acos kx cot 3 y acos t kx 4 emitted by four different sources S S S3 and S4 respectively interference phenomena would be observed in space under appropriate conditions when Source S emits wave 1 and S emits wave 2 Source S3 emits wave 3 and S4 emits wave 4 Source S emits wave 2 and S4 emits wave 4 S4 emits waves 4 and S3 emits waves 3

8 A tuning fork of frequency 512 Hz is vibrated with a sonometer wire and 6 beats per second are heard The beat frequency reduces if the tension in the string is slightly increased The original frequency of vibration of the string is a 506 Hz b 512 Hz c 518 Hz d 524 Hz

The displacement harmonic wave is y sin 20 y in cm produced by a simple 10 The sin 2000nt T 17 periodic time and maximum velocity of the particles in the medium will respectively be 10 3 s and 330 m s 10 4 s and 20 m s 10 3 s and 200 m s 10 2 s and 2000 m s

The equation of a progressive wave is given by y a sin 628t 31 4x If the distances are expressed in cm and time in seconds then the wave velocity will be 314 cm s 628 cm s 20 cm s 400 cm s

17 A wire is 4 m long and has a mass 0 2 kg The wire is kept horizontally A transverse pulse is generated by plucking one end of the taut tight wire The pulse makes four trips back and forth along the cord in 0 8 sec The tension is the cord will be a 80 N b 160 N c 240 N d 320 N

What happens when the two waves above run into each other a The waves collide and temporarily cancel each other out b The waves reflect off of each other and have no effect on the amplitude c The waves collide and destroy each other d The waves collide and temporarily add their amplitudes together

If the frequency of a wave in a medium is doubled increased by a factor of 2 what will happen to the wavelength a The wavelength will decrease by a factor of 4 b The wavelength will also increase by a factor of 2 Oc The wavelength will decrease by a factor of 2 d The wavelength will remain the same

16 Two mechanical waves y 2 sin 2x 50t 2x Y 4 sin 2 ax 100t propagate in a medium with same speed Choose the correct statement a The ratio of their intensities is 1 16 b The ratio of their intensities is 1 4 c The value of a is 3 units d The value of a is 2 units

According to the Doppler effect what happens to the frequency of a wave if the source is moving toward the receiver a It decreases b It behaves unpredictably c It stays the same d It increases

A couple students are sending waves down a length of string The students want to change the speed of the wave so they change the frequency of the waves but they notice the wave speed remains constant regardless of the frequency Which answer best describes why the students are not getting different speeds a They are not creating waves with large enough amplitude so the waves speed remains constant b The rope has a defect and they must obtain a new rope to get better data Oc As they increase the frequency the wavelength increases too in order to keep the wave speed constant d The speed of the wave only depends on the medium in which it travels so changing frequency has no effect

Q 14 An organ pipe P closed at one end vibrating in its first overtone and another pipe P2 open at the both ends vibrating in its third overtone are in resonance with a given tuning fork The ratic 3 of the length of P to that of P2 is then n

Electric field associated with a light is E 100 sin 6 28 x 10 5 t 3 14 x 10 t V m If this light incident on a metal of work function 2eV find stopping potential 1 3 1 volt 2 2 1 volt 3 5 1 volt 4 None of these orifera faya ut Aufafea E 100 sin 6 28 x 10 5 t 3 14 x 10 t V m 1 3 1 volt 3 5 1 volt fara dari at det for all and 2 2 1 volt 4 None of these

In YDSE both slits produce equal intensities on the screen A 100 transparent thin film is placed in front of one of the slits Now the intensity on the centre becomes 25 of the previous intensity The wavelength of light is 4000 and refractive index 1 5 The minimum thickness of the glass slab is 1 23 x 10 7 m 2 67 x 10 7 m 4 x 10 7 m None of these Marks 4 1