Question:
What type of waves can travel in vacuum? Give example(s).
Answer:
Electromagnetic waves can travel in vacuum. Sun light, X-rays are examples of electromagnetic waves.
Sound
Q 1.
Fill in the blanks :
If a body repeats its back and forth, to and fro or up and down motion along a certain path, about a fixed point, in a certain time interval then the motion of such objects is said to be _____________.
Q 2.
What is speed of sound in air?
Q 3.
Fill in the blanks :
The principle on which stethoscope works is _____ (reflection/ multiple reflection)
Q 4.
What type of wave is represented by density- distance graph?
Q 5.
Distinguish between loudness and intensity of sound.
Q 6.
Fill in the blanks :
In the case of ____________ wave, distance between two consecutive crests or troughs is known as wavelength.
Q 7.
What is Sound? Why it is important for us?
Q 9.
What are ultrasonics?
Q 10.
What are wavelength, frequency, time period and amplitude of a sound wave?
Q 11.
What is reverberation?
Q 12.
What is audible range ?
Q 13.
Fill in the blanks :
RADAR (Radio Detection And Ranging) works on _____________ principle which is used to determine the velocities and movement of aircrafts.
Q 14.
How is ultrasound used for cleaning ?
Q 15.
Why are the ceilings of concert halls curved ?
Q 16.
Draw a curve showing density or pressure variations with respect to distance for a disturbance produced by sound.Mark the position of compression and rarefaction on this curve.Also define wavelengths and time period using this curve.
Q 17.
What is infrasonic? Give an example.
Q 18.
Radio Ceylon broadcasts at 25 m.What is the frequency of the station ?
Q 19.
An engine is approaching a hill at constant speed.When it is at a distance of 0.9 km,it blows a whisde,whose echo is heard by the driver after 5 s.If the speed of sound is 340 m/s,calculate the speed of the engine.
Q 20.
Distinguish between loudness and intensity of sound.
Q 21.
Cite an experiment to show that sound needs a material medium for its propagation.
Q 23.
How can you make a building sound proof ?
Q 24.
Fill in the blanks :
A ________ (pulse/wave) is a disturbance which is sudden and lasts for a short duration of time.
Q 25.
Fill in the blanks :
In a __________ wave the particles of the medium oscillate in a direction perpendicular to the direction in which the wave propagates.
Q 26.
Fill in the blanks :
The distance between two consecutive compressions or two consecutive rarefactions is called the ______________.
Q 27.
Fill in the blanks :
Loudness of sound is measured in ___________.
Q 28.
What is a mechanical wave?
Q 29.
A sound wave travels at a speed of 339 ms
–1. If its wavelength is 1.5 cm, what is the frequency of the wave?
Q 30.
A boat anchor is rocked by waves whose consecutive crests are 100 m apart.If the wave speed of the moving crests is 20 m/s,calculate the frequency at which the boat rocks.
Q 31.
What are wavelength,frequency,time period and amplitude of a sound wave ?
Q 32.
What is sound barrier ?
Q 33.
What is persistence of hearing ?
Q 34.
What is the minimum distance of the obstacle from the source of sound for hearing distinct echo ?
Q 35.
There are no echoes produced in small living rooms.Explain why echoes are produced only in large galleries and halls.
Q 36.
What are transverse waves ?
Q 37.
Discuss the structure of human ear from auditory aspect only.
Q 38.
We see flash earlier than the thunder.Discuss.
Q 39.
Fill in the blanks :
A ________ (pulse/wave) is a form of disturbance which travels through a medium as a result of repetitive oscillations of the particles of the medium.
Q 40.
Fill in the blanks :
Number of oscillations completed by the oscillator in one second is known as ___________.
Q 41.
Fill in the blanks :
Sound, compressional waves in springs are examples of _____________.
Q 42.
What type of waves can travel in vacuum? Give example(s).
Q 43.
Three persons, A, B and C are made to hear a sound travelling through different mediums as given below:
| Persons | Medium |
| A | Iron Rod |
| B | Air |
| C | Water |
Who will hear the sound first? Why?
Q 44.
What is a wave number?
Q 45.
How are the wavelength and frequency of a sound wave related to its speed?
Q 46.
A hospital uses an ultrasonic scanner to locate tumors in a tissue. What is the wavelength of sound in a tissue is which the speed of sound is 1.7 km/s. The operating frequency of the scanner is 4.2 MHz. (1MHz = 10
6 Hz).
Q 47.
A hospital uses an ultrasonic scanner to locate tumours in a tissue.What is the wavelength of sound in a tissue in which the speed of sound is 1.7 km/s ? The operating frequency of the scanner is 4.2 MHz.
Q 48.
What is sound and how is it produced ?
Q 49.
Explain the working and application of a sonar.
Q 50.
Explain how the human ear works.
