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CERN Large Hadron Collider

Why is the Large Hadron Collider as large as it is?  I heard today that the actual accelerator portion is only 40 Meters long, the rest is (mostly) magnets that steer the particles, so why does the accelerator need to be 17 miles in circumference?  Does making it larger provide any advantages?


(asked Rick)

A fill up exercise for class 9 Physics from the chapter “Sound”

Dear students,

Find below some of the fill in the blanks questions  from the chapter sound. (Class 9 Science) Practisinf fill in the blanks typwe questions helps better comprehension and thorough reading of the text book. As a follow up you can try making more fill in the blanks type questions yourself from the textbook.



  1. ______ is a form of energy which produces a sensation of hearing to our ears.
  2. λ is a symbol of representing _____________.
  3. __________ is the reciprocal of frequency.
  4. Mechanical waves are of two types; _____________ and ______________.
  5. Sound waves travel in the form of ____________ and __________________.
  6. Transverse waves propagate in the form of _________ and _____________.
  7. The maximum displacement of the wave from mean position is called ______________.
  8. Number of vibrations completed in one second is called ________________.
  9. The distance between two consecutive compressions or two consecutive rarefactions is called ______________.
  10. Sound of frequency below 20 Hz is called _____________
  11. velocity of sound = ___________ x wavelenth
  12. Sound cannot travel in _____________
  13. Sound of frequency greater than 20 kHz is called ___________
  14. _______________ is used to check abnormalities of fetus.
  15. SI unit of frequency is _________.
  16. ____________ is a device used to measure the depth of sea.
  17. SONAR’s full form is __________________________________
  18. Sound travels fastest in ____ medium
  19. Loudness of sound depend on _____ of vibration.
  20. Audible range for human beings is from _ Hz to ___ Hz.
  21. Bats detect their prey using ___________– waves.
  22. Sound heard after reflection from an obstacle or boundary is called ________-.
  23. The persistence of sound after the source has stopped vibrations is called ________.
  24. ___________ is a device used by doctors and its working is based on multiple reflection of sound.
  25. Loudness of sound is determined by the ___________ of vibrations.
  26. Checking the functioning of heart with the help of ultrasound is called ________________
  27. The outer ear is also called ________
  28. Another function of human ear is to _____________ our body.
  29. _______ of ear collects sound from the surroundings.
  30. Ultrasound are produced by some animals like __________, _____________ and _____________.
  31. Electrical signals from ear are send to the brain via _____________
  32. The three bones of the ear which amplifies the vibrations are _______ , ______________ and ____________.
  33. ______________ converts sound into electrical signals.
  34. The smallest bone in ear is __________ which is also the smallest bone in human body.
  35. ____________ are regions of higher density and pressure when sound propagates through a medium.

A Few Questions from Previous Board Papers and Answers Posted by Bright students

(A request to all students who have finished revising Physics; Now it’s time to practice Previous Question papers and sample papers. Practice to finish the questions within the stipulated time and with perfection)

Solved paper

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