Untitled Flashcard Set

1. General Properties of Waves

  • Definition: A wave is a disturbance that transfers energy from one point to another without the permanent transfer of matter.

  • Types of Waves:

    • Mechanical Waves: Require a medium (solid, liquid, or gas) to travel (e.g., sound, water waves).

    • Electromagnetic (EM) Waves: Can travel through a vacuum and do not require a medium (e.g., light, X-rays).

  • Wave Motion:

    • Transverse Waves: The displacement of the medium is perpendicular to the direction of energy transfer (e.g., waves on a string, light waves).

    • Longitudinal Waves: The displacement of the medium is parallel to the direction of energy transfer, consisting of compressions and rarefactions (e.g., sound waves).

  • Wave Equation: The speed of a wave can be calculated using v = f \lambda, where:

    • v is the wave speed.

    • f is the frequency (measured in Hertz, Hz).

    • \lambda is the wavelength.

2. Wave Interactions

  • Refraction: The change in direction of a wave as it passes from one medium to another at an angle. This is caused by a change in the wave's speed. For example, light bends when moving from air into water because it slows down.

  • Diffraction: The bending or spreading of waves as they pass around the edge of an obstacle or through a narrow opening. The amount of diffraction depends on the size of the gap relative to the wavelength (\lambda).

  • Absorption: The process by which a medium takes up the energy of a wave. When light hits an object and is absorbed, its energy is typically transformed into internal energy (heat).

3. Optics and Lenses

  • Focal Point (F): The point at which light rays meet (converge) or from which they appear to originate (diverge) after passing through a lens.

  • Convex Lenses (Converging):

    • Thicker in the middle than at the edges.

    • They converge parallel light rays toward a focal point on the opposite side of the lens.

    • Used to treat hyperopia (farsightedness) and in magnifying glasses.

  • Concave Lenses (Diverging):

    • Thinner in the middle and thicker at the edges.

    • They cause parallel light rays to spread out (diverge) so that they appear to come from a focal point in front of the lens.

    • Always produce virtual, upright, and smaller images. Used to treat myopia (nearsightedness).

4. Sound Waves

  • Nature of Sound: Sound is a longitudinal mechanical wave produced by vibrating objects.

  • Properties:

    • Pitch: Directly related to the frequency (f) of the vibration. Higher frequency results in a higher pitch.

    • Loudness: Related to the amplitude of the wave. A larger amplitude carries more energy and is perceived as louder.

  • Propagation: Sound requires a medium to travel. It travels fastest in solids due to the close proximity of particles and slowest in gases.