### Revision videos

#### Waves

28 understand and use the terms amplitude, frequency, period, speed and wavelength

29 identify the different regions of the electromagnetic spectrum and describe some of their applications

30 use the wave equation

31 recall that a sound wave is a longitudinal wave which can be described in terms of the displacement of molecules

32 use graphs to represent transverse and longitudinal waves, including standing waves

33 explain and use the concepts of wavefront, coherence, path difference, **superposition** and phase

34 recognise and use the relationship between phase difference and path difference

35 explain what is meant by a standing (stationary) wave, investigate how such a wave is formed, and identify nodes and antinodes

36 recognise and use the expression for refractive index , determine refractive index for a material in the laboratory, and predict whether total internal reflection will occur at an interface using critical angle

37 investigate and explain how to measure refractive index

38 discuss situations that require the accurate determination of refractive index

39 investigate and explain what is meant by *plane polarised light*

40 investigate and explain how to measure the rotation of the plane of polarisation

41 investigate and recall that waves can be diffracted and that substantial diffraction occurs when the size of the gap or obstacle is similar to the wavelength of the wave

42 explain how diffraction experiments provide evidence for the wave nature of electrons

43 discuss how scientific ideas may change over time, for example, our ideas on the particle/wave nature of electrons

44 recall that, in general, waves are transmitted and reflected at an interface between media

45 explain how different media affect the transmission/reflection of waves travelling from one medium to another

46 explore and explain how a pulse-echo technique can provide details of the position and/or speed of an object and describe applications that use this technique

47 explain qualitatively how the movement of a source of sound or light relative to an observer/detector gives rise to a shift in frequency (Doppler effect) and explore applications that use this effect

48 explain how the amount of detail in a scan may be limited by the wavelength of the radiation or by the duration of pulses

49 discuss the social and ethical issues that need to be considered, eg, when developing and trialling new medical techniques on patients or when funding a space mission

#### DC Electricity

50 describe electric current as the rate of flow of charged particles and use the expression

51 use the expression

52 recognise, investigate and use the relationships between current, voltage and resistance, for series and parallel circuits, and know that these relationships are a consequence of the conservation of charge and energy

53 investigate and use the expressions , . Recognise and use related expressions eg and

54 use the fact that resistance is defined by and that Ohm’s law is a special case when

55 demonstrate an understanding of how ICT may be used to obtain current-potential difference graphs, including non-ohmic materials and compare this with traditional techniques in terms of reliability and validity of data

56 interpret current-potential difference graphs, including non-ohmic materials

57 investigate and use the relationship

58 investigate and explain how the potential along a uniform current-carrying wire varies with the distance along it and how this variation can be made use of in a potential divider

59 define and use the concepts of emf and internal resistance and distinguish between emf and terminal potential difference

60 investigate and recall that the resistance of metallic conductors increases with increasing temperature and that the resistance of negative temperature coefficient thermistors decreases with increasing temperature

61 use to explain the large range of resistivities of different materials

62 explain, qualitatively, how changes of resistance with temperature may be modelled in terms of lattice vibrations and number of conduction electrons

#### Nature of light

63 explain how the behaviour of light can be described in terms of waves and photons

64 recall that the absorption of a photon can result in the emission of a photoelectron

65 understand and use the terms threshold frequency and work function and recognise and use the expression

66 use the non-SI unit, the electronvolt (eV) to express small energies

67 recognise and use the expression to calculate the highest frequency of radiation that could be emitted in a transition across a known energy band gap or between known energy levels

68 explain atomic line spectra in terms of transitions between discrete energy levels

69 define and use radiation flux as power per unit area

70 recognise and use the expression

71 explain how wave and photon models have contributed to the understanding of the nature of light

72 explore how science is used by society to make decisions, for example, the viability of solar cells as a replacement for other energy sources, the uses of remote sensing