P5: Waves in matter

P5.1 Wave behaviour

PM5.1i recall and apply: wave speed (m/s) = frequency (Hz) x wavelength (m)

P5.1a describe wave motion in terms of amplitude, wavelength, frequency and period

P5.1b define wavelength and frequency

P5.1c describe and apply the relationship between these and the wave velocity

P5.1d apply formulae relating velocity, frequency and wavelength (M1c, M3c)

P5.1e describe differences between transverse and longitudinal waves

P5.1f show how changes, in velocity, frequency an wavelength, in transmission of sound waves from one medium to another, are inter-related (M1c, M3c)

P5.1g describe the effects of reflection, transmission and absorption of waves at material interface

P5.1h describe, with examples, processes which convert wave disturbances between sound waves and vibrations in solids

P5.1i explain why such processes only work over a limited frequency range, and the relevance of this to human hearing

P5.1j describe how ripples on water surfaces are used to model transverse waves whilst sound waves in air are longitudinal waves, and how the speed of each may be measured

P5.1k describe evidence that in both cases it is the wave and not the water or air itself that travels.The basic concept of a wave; this topic will introduce them to reflection, refraction, diffraction and absorption in both mechanical and electromagnetic waves. It will also approach the evidence which originally led scientists to deduce that light was a wave. Learners should also be aware of the equations governing all waves: wave speed (m/s) = frequency (Hz) x wavelength (m), and the important difference between mechanical waves, which require a medium to travel through, and electromagnetic waves, which do not.

 P5.2 The electromagnetic spectrum

P5.2a recall that electromagnetic waves are transverse and are transmitted through space where all have the same velocity

P5.2b explain that electromagnetic waves transfer energy from source

P5.2c apply the relationship between frequency and wavelength across the electromagnetic spectrum (M1a, M1c, M3c)

P5.2d describe the main grouping of the electromagnetic spectrum and that these groupings range from long to short wavelength and from low to high frequencies

P5.2e describe that our eyes can only detect a limited range of the electromagnetic spectrum

P5.2f recall that light is an electromagnetic wave

P5.2g give examples of some practical uses of electromagnetic waves in the radio, micro-wave, infra-red, visible, ultra-violet, X-ray and gamma-ray regions

P5.2h describe how ultra-violet waves, X-rays and gamma-rays can have hazardous effects, notably on human bodily tissues

P5.2i explain, in qualitative terms, how the differences in velocity, absorption and reflection between different types of waves in solids and liquids can be used both for detection and for exploration of structures which are hidden from direct observation, notably in our bodies

P5.2j recall that radio waves can be produced by, or can themselves induce, oscillations in electrical circuits. the electromagnetic spectrum and the fact that the effect EM radiation has on a substance depends on its energy, which in turn depends upon its frequency/wavelength. The effects and characteristics of the different areas of the EM spectrum will be covered in some detail.

 P5.3 Wave interactions

P5.3a recall that different substances may absorb, transmit, refract, or reflect electromagnetic waves in way

P5.3b explain how some effects are related to differences in the velocity of electromagnetic waves in different substances

P5.3c use ray diagrams to illustrate reflection, refraction and the similarities and differences between convex and concave lenses (qualitative only)

P5.3d construct two-dimensional ray diagrams to illustrate reflection and refraction (qualitative only – equations not needed) (M5a, M5b)

P5.3e explain how colour is related to differential absorption, transmission and reflection

This topic introduces reflection, refraction and diffraction, as well as exploring the behaviour of materials that react differently to different frequencies of light and sound. In much the same way as we saw that the atmosphere transmits, reflects and absorbs various frequencies within the electromagnetic spectrum, coloured objects reflect, transmit and absorb different frequencies of visible light.