Properties of Waves

The prime properties of waves are as follows:

Amplitude – Wave is an energy transport phenomenon. Amplitude is the height of the wave, usually measured in metres. It is directly related to the amount of energy carried by a wave.

Wavelength – The distance between identical points in the adjacent cycles of crests of a wave is called a wavelength. It is also measured in metres.

Period – The period of a wave is the time for a particle on a medium to make one complete vibrational cycle. As the period is time, hence is measured in units of time such as seconds or minutes.

Frequency – Frequency of a wave is the number of waves passing a point in a certain time. The unit of frequency is hertz (Hz) which is equal to one wave per second.

The period is the reciprocal of the frequency and vice versa.

Speed – The speed of an object means how fast an object moves and is usually expressed as the distance travelled per time of travel. The speed of a wave refers to the distance travelled by a given point on the wave (crest) in a given interval of time.

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Short Notes of Chapter Waves Class 11 Physics download pdf free

1. Introduction to Waves:

• A wave is a disturbance that transfers energy through a medium or space without a net movement of particles.
• Examples include sound waves, light waves, and water waves.

2. Types of Waves:

• Mechanical Waves:
  • Require a medium (solid, liquid, or gas) for propagation.
  • Examples: sound waves, water waves.
• Electromagnetic Waves:
  • Can propagate through a vacuum (no medium).
  • Examples: light waves, radio waves.

3. Characteristics of Waves:

• Amplitude (A):
  • Maximum displacement from the equilibrium position.
• Frequency (f):
  • Number of oscillations per unit time (measured in Hertz, Hz).
• Wavelength ($\lambda$):
  • Distance between two consecutive points in a wave in the same phase.

4. Wave Equation:

• $v=f\cdot \lambda$
• The speed ($v$) of a wave is the product of its frequency ($f$) and wavelength ($\lambda$).

5. Types of Mechanical Waves:

• Transverse Waves:
  • Particles move perpendicular to the direction of the wave.
  • Examples: light waves.
• Longitudinal Waves:
  • Particles move parallel to the direction of the wave.
  • Examples: sound waves.

6. Wave Superposition:

• When two waves meet, their displacements combine through superposition.
• Interference can be constructive or destructive.

7. Reflection and Refraction:

• Reflection:
  • Bouncing back of a wave when it encounters a boundary.
• Refraction:
  • Bending of a wave as it passes from one medium to another.

8. Standing Waves:

• Result from the interference of two identical waves traveling in opposite directions.
• Nodes and antinodes are characteristic points in standing waves.

9. Doppler Effect:

• Change in frequency or wavelength in relation to an observer moving relative to the source of the wave.
• Applicable to both sound and light waves.

10. Wavefronts:

• Imaginary lines that connect points of a wave in phase.
• Spherical wavefronts emanate from a point source.

11. Huygens’ Principle:

• Every point on a wavefront acts as a source of secondary wavelets that spread out in a spherical manner.

12. Polarization:

• Process of restricting the vibrations of a transverse wave to one direction.
• Commonly observed in light waves.

13. Applications:

• Waves play a crucial role in various technologies, including telecommunications, medical imaging, and seismic exploration.

14. Interference:

• Constructive Interference:
  • Occurs when waves in phase reinforce each other, resulting in a wave of increased amplitude.
• Destructive Interference:
  • Occurs when waves out of phase cancel each other, resulting in a wave of decreased amplitude or no wave at all.

15. Diffraction:

• Bending of waves around obstacles and the spreading of waves when they encounter an opening.
• More pronounced for longer wavelengths.

16. Electromagnetic Spectrum:

• Range of all possible frequencies of electromagnetic radiation.
• Includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.

17. Wave-Particle Duality:

• Particles, such as photons, exhibit both wave-like and particle-like properties.
• Central concept in quantum mechanics.

18. Resonance:

• Enhancement of oscillations when the frequency of an applied force matches the natural frequency of a system.
• Commonly observed in musical instruments.

19. Wave Intensity:

• The energy transported by a wave per unit of time and per unit of surface area.
• Proportional to the square of the amplitude.

20. Rayleigh Criterion:

• Criterion for the resolution of two adjacent objects in optical systems.
• Determines the minimum angular separation required to distinguish between two points.

21. Waveguides:

• Structures designed to guide and confine waves, often used in telecommunications.
• Examples include optical fibers and transmission lines.

22. Ultrasonics:

• Application of ultrasound waves in medical imaging, cleaning, and industrial testing.
• Utilizes the property of high-frequency sound waves.

23. Acoustic Resonance:

• Phenomenon where an object vibrates at its natural frequency, often leading to the amplification of sound.
• Important in musical instruments and architectural acoustics.

24. Seismic Waves:

• Waves that travel through the Earth in response to geological phenomena such as earthquakes.
• Classified into P-waves and S-waves based on their characteristics.

25. Wave Equations:

• Mathematical representations describing the behavior of waves, such as the wave equation for transverse waves and the Schrödinger equation in quantum mechanics.

Wave Motion Notes With JEE NEET MCQS Physics Class 11 CBSE Study Material Full Chapter Download pdf-Anand Classes