Lecture-5
Physics
1. _________ is the distance between two nearest particle of the medium, vibrating in same phase. – Wavelength
2. ________ of vibration of a particle is defined as the number of vibrations completed by the particle in one second. – Frequency
3. Velocity of Wave- Frequency * Wavelength
4. What is the nature of the Sound Wave ?- It is longitudinal mechanical wave.
5. The longitudinal mechanical waves which lie in the range of _______are called audible or sound waves. -20 Hz to 20000 Hz
6. The longitudinal mechanical waves having frequencies less than 20 Hz are called __________. – Infrasonic
7. Infrasonic waves are produced by :
· Earthquakes
· Volcanic eruption
· Ocean Waves
· Elephants
· Whales
8. The longitudinal waves having the frequencies greater than 20000 Hz are called _________. – Ultrasonic Waves
9. ___________ cannot detect ultrasonic waves . – Human Ear
10. _________ can detect ultrasonic waves. – Dog , Cat, Bat , Mosquito etc.
11. _________ produce ultrasonic waves . – Bat
12. Ultrasonic waves are used for :
· Sending Signals
· Measuring depth of the sea
· Cleaning Clothe, Machinery Parts of Clocks , Removing Lamp shoot from Chimney of Factories
· Ultrasonography
13. Speed of the sound is maximum in _______. –Solids
14. Speed of sound is minimum in ________. – Gases
15. Speed of sound in air is ________. – 332 m/s
16. Speed of sound in water is ______.-1483 m/s
17. Speed of sound in solids is ______. – 5130 m/s
18. Speed of sound depends upon _________. – Elasticity and density of medium.
19. When sound enters from one medium to another medium , its speed and wavelength changes but ________ remains unchanged. –Frequency
20. Speed of sound remains unchanged by the increase or decrease of __________. –Pressure
21. The speed of sound increases with the increase in the __________ of the medium. – Temperature
22. The speed of sound in air increases by ________ when the temperature is increased by 1 0C. – 0.61m/s
23. The speed of is more in _____ air than in _____ air because density of humid air is less than the density of dry air. – humid, dry
24. The speed of _______ is very slow as compared o speed of ______ in the air. – Sound , Light
25. The speed of sound depends upon :
· Modulus of elasticity of medium
· Pressure
· Density of Gases
· Ration of Specific Heats
26. The loudness of sound depends upon which factors ? -Intensity of sound wave as well as sensitivity of ear.
27. ________ is that characteristic of sound which distinguishes a sharp sound from a grave sound .- Pitch
28. Pitch depends upon the _____________- Frequency of Sound Waves
29. _______ is that characteristic of sound which enable us to distinguish between sound produced by tow source having same intensity and pitch. – Quality
30. A body moving with supersonic speed in air leaves behind it a conical region of disturbance which spreads continuously. Such a disturbance is called __________. –Shock Waves
31. The speed of supersonic wave is measured in ______.-Mach number
32. Mach Number = Velocity of source /Velocity of Sound
33. If Mach number >1 , body is called ________.- Supersonic
34. If Mach number >5 , body is called ________. – Hypersonic
35. If Mach number is <1 body is called _________. –Subsonic
36. When sound waves incidence on any rigid surface , it returns to its original position, this is called ___________. –Reflection of Sound Wave
37. The repetition of sound due to reflection of sound waves is called _______. –Echo
38. At moon echo is not heard due to _________. -Absence of atmosphere.
39. The quality in a sound of being deep, full, and reverberating is called ________. –Resonance
40. What is the full form of SONAR ?- Sound Navigation and Ranging
41. Uses of SONAR :
· To measure the depth of Sea.
· To locate enemy submarines
· To locate shipwrecks.
42. SONAR produces __________. – Ultrasonic Sound Waves
43. If there is a relative motion between the source of sound and observer , the apparent frequency of sound heard by the observer is different from the actual frequency of sound emitted by the source. This phenomenon is called ______. –Doppler Effect
44. Under Doppler Effect when the distance between the source and observer decreases , the apparent frequency _________. Increases.
45. Uses of Doppler Effect
· By the police to check over speeding of vehicles.
· At airport to guide the aircraft.
· To study heart beats and blood flow on the different parts of body.
46. _______ is a form of energy which flows from hotter to colder body by the virtue of temperature difference. – Heat
47. Heat is due to the __________ of the molecules constituting the body. – Kinetic Energy
48. What are the units of heat ?- Calorie (cal) , Kilocalorie ( kcal) , Joule (J)
49. 1 cal= 4.18 Joule
50. K kcal= 1000 cal