Mechanical waves are one of the most numerically dense chapters in NEB Grade XII Physics, covering wave motion, the speed of sound in different media, standing waves in strings and pipes, and the Doppler effect. Board exams draw heavily from this chapter almost every year — expect at least one 2-mark numerical on wave speed or wavelength, and often a 3-mark question on resonance in air columns or vibrating strings. The video walkthroughs below cover real past-paper numericals and derivations, worked step by step the way you’d want to show your answer sheet. Use the tabs to jump between Numericals and Derivations, or search by year or topic — for example, type “2081” to see every video from that year’s paper, or “resonance” to pull up string and pipe problems. Pair these videos with the written notes and Questions Bank for this chapter to build both your calculation speed and your conceptual understanding before the exam.
Numericals
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