General Properties of WavesCambridge IGCSE Physics: Flashcards
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What is the fundamental property of all waves regarding energy and matter?
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- What is the fundamental property of all waves regarding energy and matter?
- Waves transfer energy without transferring matter. The medium vibrates but the material itself does not move along with the wave.
- Define wavelength.
- Wavelength is the distance between two adjacent points that are in phase, such as the distance from one crest to the next crest, or one trough to the next trough. It is measured in metres and represented by the symbol λ.
- What is amplitude of a wave?
- Amplitude is the maximum displacement of a particle from its equilibrium position. It is a measure of the height of a crest or depth of a trough from the centre line, measured in metres.
- Define frequency of a wave.
- Frequency is the number of complete waves passing a point per unit time, or the number of vibrations per second. It is measured in hertz (Hz).
- State the wave equation and identify what each symbol represents.
- v = fλ, where v is wave speed (m/s), f is frequency (Hz), and λ is wavelength (m).
- What is a wavefront?
- A wavefront is a line or surface joining all points that are at the same stage of vibration (in phase). Wavefronts are perpendicular to the direction of energy propagation.
- Define a transverse wave and give three examples.
- A transverse wave is a wave where the direction of vibration is perpendicular (at right angles) to the direction of propagation. Examples include: electromagnetic radiation, water waves, and seismic S-waves.
- Define a longitudinal wave and give two examples.
- A longitudinal wave is a wave where the direction of vibration is parallel to the direction of propagation. Examples include: sound waves and seismic P-waves.
- What happens to a wave when it undergoes reflection at a plane surface?
- The wave bounces off the surface. The angle of incidence equals the angle of reflection, and the wave returns into the medium from which it came without change in speed or frequency.
- Explain refraction of waves.
- Refraction is the change in direction of a wave when it enters a medium where its speed changes. The wavelength and speed change, but frequency remains constant. The wave bends towards the normal if it slows down, or away from the normal if it speeds up.
- What is diffraction and when does it occur?
- Diffraction is the spreading out of waves when they pass through a gap or around an edge. It occurs when the size of the gap or edge is comparable to or smaller than the wavelength.
- Describe how a ripple tank demonstrates reflection of waves.
- A ripple tank contains water and shows waves reflecting off a plane barrier or curved surface placed in the water. The reflected waves can be observed and photographed to show that the angle of incidence equals the angle of reflection.
- How does a ripple tank demonstrate refraction?
- A ripple tank shows refraction when a wave travels from deep water into shallow water (or vice versa) over a sloping bottom or step. The wave changes speed and direction as it enters the region of different depth, demonstrating the change in wavelength whilst frequency remains constant.
- How does the size of a gap affect diffraction through it?
- Diffraction through a gap increases significantly when the gap width is reduced. Maximum diffraction occurs when the gap width is similar to or smaller than the wavelength. As the gap becomes wider relative to the wavelength, diffraction decreases.
- How does wavelength affect diffraction at an edge or through a gap?
- Longer wavelengths diffract more than shorter wavelengths. For a given gap or edge size, a wave with a longer wavelength will spread out more significantly than a wave with a shorter wavelength.
- Describe how a ripple tank demonstrates diffraction due to a gap and due to an edge.
- For a gap: waves passing through a narrow gap spread out (diffract) on the other side, creating a semicircular wave pattern. For an edge: waves passing the edge of a barrier spread out behind the barrier. Both effects are more pronounced when the wavelength is larger or the gap/edge is narrower.