Physics Notes - Waves and Optics

1. Difference Between Longitudinal and Transverse Waves Longitudinal Waves: Oscillations occur parallel to the direction of wave propagation. Example: Sound waves in air. Transverse Waves: Oscillations occur perpendicular to the direction of wave propagation. Example: Light waves, water waves. 2....

1. Difference Between Longitudinal and Transverse Waves Longitudinal Waves: Oscillations occur parallel to the direction of wave propagation. Example: Sound waves in air. Transverse Waves: Oscillations occur perpendicular to the direction of wave propagation. Example: Light waves, water waves. 2. Wave Diagram Key Elements of a Wave: Wavelength ( 𝜆 λ): The distance between two consecutive crests or troughs. Amplitude: The height from the normal to the crest/trough. Frequency (f): Number of wave cycles per second. Normal: A reference line indicating equilibrium position. (Include a simple sine wave diagram showing these elements.) 3. Definitions Amplitude: The maximum displacement of a point on the wave from the normal. Wavelength: The distance over which the wave's shape repeats. Frequency: The number of complete waves passing a point per second (measured in Hz). Normal: The equilibrium position or baseline of the wave. 4. Wave Speed Formula: 𝑣 = 𝑓 × 𝜆 v=f×λ Where: 𝑣 v: Wave speed (m/s) 𝑓 f: Frequency (Hz) 𝜆 λ: Wavelength (m) 5. Sound Production and Properties Production: Vibrations in a medium create compressions and rarefactions. Speed: Depends on the medium—faster in solids, slower in gases. Example: ~343 m/s in air at 20°C. 6. Compressions and Rarefactions Compressions: Regions where particles are close together in a longitudinal wave. Rarefactions: Regions where particles are spread apart. 7. Uses of Sound Waves Ultrasound: Used in medical imaging and cleaning. Sonar: Used in navigation and detecting underwater objects. Evaluation: Both techniques are non-invasive and effective but depend on wave properties and require skilled operation. 8. Formation of an Image in a Plane Mirror Light reflects off the mirror at equal angles. The image appears as the same size and distance behind the mirror. 9. Law of Reflection Law: Angle of incidence = Angle of reflection. Explanation: Images form because light reflects predictably, allowing the brain to perceive the position of the source. 10. Refraction Definition: Bending of light as it passes from one medium to another. (Include a diagram showing light bending at the interface of two media.) 11. Real vs Apparent Depth Real Depth: Actual depth of an object in water. Apparent Depth: Perceived depth due to refraction. 12. Total Internal Reflection and Critical Angles Total Internal Reflection: Occurs when light reflects entirely within a medium. Critical Angle: Minimum angle of incidence for total internal reflection. (Include a diagram showing both concepts.) 13. Optical Fibres Use total internal reflection for data transmission. Evaluation: Fast, reliable, and immune to electromagnetic interference. 14. Diffraction Definition: Spreading of waves as they pass through a gap or around an edge. Example: Ripple tank experiments show water waves spreading after passing through a narrow slit. 15. Key Anatomical Parts of the Eye Cornea: Refracts light into the eye. Lens: Focuses light onto the retina. Retina: Detects light and sends signals to the brain. Iris: Regulates the amount of light entering. 16. Image Formation by the Eye The lens bends light to focus it on the retina, forming a clear image. The eye functions as a convex lens. 17. Correction of Vision Long Sight (Hyperopia): Corrected with convex lenses. Short Sight (Myopia): Corrected with concave lenses.