Скачать или смотреть Multiple Choice Questions | Chapter 9 | Waves | Physics 11th | National Book Foundation | FBISE

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Q. Encircle the correct option.
On doubling amplitude of the wave energy is increased ______ times.
(a) 1/2 (b) 2 (c) 4 (d) remains constant
Two waves, each with amplitude of 0.5m are superimposed with constructive interference such that they are in phase. What is the resultant amplitude?
(a) 0.25m (b) 0.5m (c) 0m (d) 1m
What happens when two sound waves of frequencies differing by more than 10Hz reach our ear simultaneously?
(a) beats are not produced (b) the waves destroy each other’s effect.
(c) interference of sound does not take place (d) beats are produced but cannot be heard
A car has two horns, one is emitting a frequency of 199Hz and the other is emitting a frequency of 203Hz. What beat frequency do they produce?
(a) 4Hz (b) 199Hz (c) 201Hz (d) 203 Hz
Which of the following frequencies are higher harmonics of a string with fundamental frequency of 150Hz?
(a) 200Hz, 300Hz (b) 300Hz, 600Hz (c) 250Hz, 450Hz (d) 250Hz, 500Hz
What is the wavelength of the third harmonic (n=3) of a standing wave established on a string of length 3m fixed at both ends?
(a) 1m (b) 1.5m (c) 2m (d) 3m
A node is a point located along the medium where there is always
(a) a double crest (b) constructive interference (c) destructive interference (d) a double rarefaction
Which phenomenon is produced when two or more waves passing simultaneously through the same medium meet up with one another?
(a) refraction (b) diffraction (c) interference (d) reflection
A standing wave is formed by waves of frequency 256Hz. The speed of the waves is 128m/s. The distance between the nodes must be
(a) 2.00m (b) 1.00m (c) 0.500m (d) 0.250m
An air column that is closed at one end is used to determine the speed of sound. The frequency of the tuning fork used is 329.6Hz. The length of the shortest air column producing the resonance is 25.0cm. The speed of the sound must be
(a) 380.6 m/s (b) 282.4 m/s (c) 3.30×〖10〗^2 m/s (d) 3.50×〖10〗^2 m/s
The intensity of beam observed through polarizer
(a) is increased (b) is decreased (c) is always zero (d) remains unchanged
Two identical waves undergo pure constructive interference. Is the resultant intensity twice that of the individual waves? Explain your answer.
Circular water waves decrease in amplitude as they move away from where a rock is dropped. Explain why.
Differentiate between constructive and destructive interference?
The frequency of a stretched string depends on its length. Give two other factors that affect the frequency of a stretched string.
What are stationary waves? How are they produced?
The pitch of the sound emitted by the siren of a moving fire engine appears to change as it passes a stationary observer. (i) Name this phenomenon. (ii) Will the crew in the fire engine notice this phenomenon? Give a reason for your answer. (iii) Give an application of this phenomenon.
How should a sound source move with respect to an observer so that the frequency of its sound does not change?
Can sound waves be polarized? Explain
Suppose that light passes through two polaroid filters whose polarization axis are parallel to each other. What would be the result?
Give any three example of a gravitational wave?
What is an interferometer?
Consider the three pairs of sunglasses below. Which pair of the glasses is capable of eliminating the glare resulting from sunlight reflecting off the calm waters of a lake? Explain you option. (The polarization axes are shown by straight lines)
Ultrasound of intensity 1.50×〖10〗^2 〖W/m〗^2 is produced by the rectangular head of a medical imaging device measuring 3.00 by 5.00 cm. What is its power output?
Two tuning forks of frequencies 440Hz and 437Hz are sounded together. How many beats will be heard over a period of 10 seconds?
Suppose that a string is 1.2m long and vibrates in first, second and third harmonic standing wave patterns. Determine the wavelength of the waves for each of the three patterns.
The string is 6.0m long and is vibrating at the third harmonic. The string vibrates up and down with 45 complete vibrational cycles in 10 seconds. Determine the frequency, period, wavelength and speed for this wave.
An air column closed at one end resonates at the second maximum or the second resonant length. The frequency of the sound wave is 1024Hz. The air temperature is 18.6℃. (a) Draw a diagram for the displacement wave pattern inside the column. (b) Calculate the speed of sound in air. (c) Calculate the wavelength. (d) Calculate the length of the closed air column.
Suppose a train that has a 150Hz horn is moving at 35.0m/s in still air on a day when the speed of sound is 340m/s. What frequencies are obtained by a stationary person at the side of the tracks (a) as the train approaches (b) after it passes (c) What frequency is observed by the train’s engineer traveling on the train?