Physics · Class 11 · Chapter 14
Waves
10 lessons 89 min 2 simulations
This chapter follows a disturbance as it travels: how the particles of a medium only oscillate while the pattern moves on, how to write a travelling wave as y = a sin(kx − ωt + φ), what fixes its speed on a string and in air, and what happens when waves meet, whether they add, reflect into standing waves with fixed nodes, or beat against each other. It builds directly on the oscillations chapter and sets up sound, strings, pipes and, later, light.
What the exam asks
NEET asks for amplitude, wavelength, frequency and speed read off a wave equation, the speed of a wave on a string from T and µ, the Newton and Laplace formulas for sound, the harmonics of strings and of closed and open pipes, the phase change on reflection, and beat frequencies. Marks are lost by mixing k with ω, by giving a closed pipe even harmonics, by thinking the source sets the wave speed, and by forgetting that a beat frequency is a difference, not a sum.
Lessons
10 lessons · 89 min
1Waves carry energy, not matterNCERT §14.17 min2Transverse and longitudinal wavesNCERT §14.27 min3Displacement relation of a progressive waveNCERT §14.38 min4Wave speed on a stretched stringNCERT §14.4, §14.4.17 min5Speed of sound: Newton and LaplaceNCERT §14.4.28 min6Principle of superpositionNCERT §14.56 min7Reflection and standing wavesNCERT §14.68 min8Harmonics of strings and pipesNCERT §14.6.112 min 1 sim9BeatsNCERT §14.711 min 1 sim10Chapter reviewMust-know facts, traps and formulas15 min