Question 8The frequency of a source of sound is 100 Hz. How many times does it vibrate in a minute?

Question

Bright Tutorials · Accepted Answer

Given,Frequency (ν) = 100 HzTime (t) = 1 min = 60 sFrequency (ν) = Number of oscillationsTotal time (t)\dfrac{	ext{Number of oscillations}}{	ext{Total time (t)}}Total time (t)Number of oscillations​OrNumber of oscillations = ν × tSubstituting we get,Number of oscillations = 100 × 60 = 6000Hence, the source vibrates 6000 times in a minute.

Web Content: Sound | Bright Tutorials

.quick-rev { background: linear-gradient(135deg, #eaf2f8, #d6eaf8); border: 2px solid var(--bt-primary-light); border-radius: 10px; padding: 20px; margin: 15px 0; }
    .quick-rev h3 { color: var(--bt-primary); margin-top: 0; }
    .quick-rev ul { margin: 0; padding-left: 20px; }
    .quick-rev li { margin-bottom: 6px; font-size: 0.92rem; }
    .keyword-tags { display: flex; flex-wrap: wrap; gap: 6px; margin: 10px 0; }
    .keyword-tags span { background: var(--bt-primary-light); color: var(--bt-primary-dark); padding: 3px 10px; border-radius: 12px; font-size: 0.78rem; font-weight: 600; }

BRIGHT TUTORIALS
  BRIGHT TUTORIALSCBSE Class IX | Academic Year 2026-20279403781999Excellence in Education
  Science | Chapter 11: SoundWeb Content &mdash; Quick Reference
  
    Chapter 11: Sound &mdash; Quick Reference

longitudinal wave
      frequency
      wavelength
      echo
      SONAR
      ultrasound
      human ear
      speed of sound

Quick Revision Points
      
        Sound: produced by vibration, needs medium, longitudinal wave (compressions + rarefactions)
v = fλ; Speed in air ≈ 344 m/s; Solids > Liquids > Gases
Loudness → amplitude; Pitch → frequency; Quality → waveform
Echo: reflected sound; min distance = 17.2 m (at v = 344 m/s, t ≥ 0.1 s)
Audible range: 20 Hz – 20 kHz; Infrasound  20 kHz
SONAR: d = vt/2; Human ear: pinna → canal → eardrum → hammer/anvil/stirrup → cochlea → auditory nerve

Exam Tips for Chapter 11
      
        Read the detailed chapter notes for complete coverage of all NCERT topics.
        Practice all NCERT in-text and back exercise questions &mdash; they are frequently asked in exams.
        Focus on comparison tables, diagrams, and definitions &mdash; these are high-scoring areas.
        For numericals (if applicable), practice at least 20 problems of varying difficulty.
        Refer to the practice question bank (200+ questions) for thorough preparation.

Related Resources
      
        Detailed Notes: ch11-sound.html
        Practice Questions: 100+ questions with answers in 05-practice-questions/
        Chapter Test: 30-mark test paper in 06-tests/chapter-tests-30marks/
        Formula Sheet: Complete formula reference in 03-teacher-aid/formula-sheet.html

BRIGHT TUTORIALSContact: 9403781999 | CBSE Class IX Coaching | 2026-2027

Sound — Question 8

Question 8

Chapter 11: Sound — Quick Reference

Quick Revision Points