3. Waves
- Syllabus
- 0625–2026–2027
- Section
- 3
- Level
- —
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In this section
Topic 3.1
3.1 General properties of waves
Objectives in this topic
3.1.1—Waves transfer energy without
- Know: waves transfer energy without transferring matter
3.1.2—What is meant by wave motion as
- Describe what is meant by wave motion as illustrated by vibrations in ropes and springs, and by experiments using water waves
3.1.3—Features of a wave in terms of
- Describe the features of a wave in terms of wavefront, wavelength, frequency, crest (peak), trough, amplitude and wave speed
3.1.4—Recall/use: for wave speed v = f λ
- Recall/use: for wave speed v = f λ
3.1.5—For a transverse wave, the direction
- Know: for a transverse wave, the direction of vibration is at right angles to the direction of propagation and understand that electromagnetic radiation, water waves and seismic S-waves (secondary) can be modelled as transverse
3.1.6—For a longitudinal wave, the direction
- Know: for a longitudinal wave, the direction of vibration is parallel to the direction of propagation and understand that sound waves and seismic P-waves (primary) can be modelled as longitudinal
3.1.7—Waves can undergo: (a) reflection at a
- Describe how waves can undergo: (a) reflection at a plane surface (b) refraction due to a change of speed (c) diffraction through a narrow gap
3.1.8—Use of a ripple tank to show: (a)
- Describe the use of a ripple tank to show: (a) reflection at a plane surface (b) refraction due to a change in speed caused by a change in depth (c) diffraction due to a gap (d) diffraction due to an edge
3.1.9—Wavelength and gap size affects
- Describe how wavelength and gap size affects diffraction through a gap
3.1.10—Wavelength affects diffraction at an
- Describe how wavelength affects diffraction at an edge
Topic 3.2.1
3.2.1 Reflection of light
Objectives in this topic
3.2.1.1—Terms normal, angle of incidence and
- Define and use the terms normal, angle of incidence and angle of reflection
3.2.1.2—Formation of an optical image by a
- Describe the formation of an optical image by a plane mirror and give its characteristics, i.e. same size, same distance from mirror, virtual
3.2.1.3—For reflection, the angle of incidence
- State: for reflection, the angle of incidence is equal to the angle of reflection; recall and use this relationship
3.2.1.4—Simple constructions, measurements and
- Use simple constructions, measurements and calculations for reflection by plane mirrors
Topic 3.2.2
3.2.2 Refraction of light
Objectives in this topic
3.2.2.1—Terms normal, angle of incidence and
- Define and use the terms normal, angle of incidence and angle of refraction
3.2.2.2—An experiment to show refraction of
- Describe an experiment to show refraction of light by transparent blocks of different shapes
3.2.2.3—Passage of light through a transparent
- Describe the passage of light through a transparent material (limited to the boundaries between two mediums only)
3.2.2.4—Meaning of critical angle
- State the meaning of critical angle
3.2.2.5—Internal reflection and total internal
- Describe internal reflection and total internal reflection using both experimental and everyday examples
3.2.2.6—Refractive index, n, as the ratio of
- Define refractive index, n, as the ratio of the speeds of a wave in two different regions
3.2.2.7—Refractive index: n = sin i / sin r
- Recall/use refractive index: n = sin i / sin r
3.2.2.8—Critical angle relation: n = 1 / sin c
- Recall/use critical angle relation: n = 1 / sin c
3.2.2.9—Use of optical fibres, particularly in
- Describe the use of optical fibres, particularly in telecommunications
Topic 3.2.3
3.2.3 Thin lenses
Objectives in this topic
3.2.3.1—Action of thin converging and thin
- Describe the action of thin converging and thin diverging lenses on a parallel beam of light
3.2.3.2—Terms focal length, principal axis and
- Define and use the terms focal length, principal axis and principal focus (focal point)
3.2.3.3—Ray diagrams for the formation of a
- Draw and use ray diagrams for the formation of a real image by a converging lens
3.2.3.4—Characteristics of an image using the
- Describe the characteristics of an image using the terms enlarged/same size/diminished, upright/inverted and real/virtual
3.2.3.5—A virtual image is formed when
- Know: a virtual image is formed when diverging rays are extrapolated backwards and does not form a visible projection on a screen
3.2.3.6—Ray diagrams for the formation of a
- Draw and use ray diagrams for the formation of a virtual image by a converging lens
3.2.3.7—Use of a single lens as a magnifying
- Describe the use of a single lens as a magnifying glass
3.2.3.8—Use of converging and diverging lenses
- Describe the use of converging and diverging lenses to correct long-sightedness and short-sightedness
Topic 3.2.4
3.2.4 Dispersion of light
Objectives in this topic
3.2.4.1—Dispersion of light as illustrated by
- Describe the dispersion of light as illustrated by the refraction of white light by a glass prism
3.2.4.2—Traditional seven colours of the
- Know the traditional seven colours of the visible spectrum in order of frequency and in order of wavelength
3.2.4.3—Recall that visible light of a single
- Recall that visible light of a single frequency is described as monochromatic
Topic 3.3
3.3 Electromagnetic spectrum
Objectives in this topic
3.3.1—Main regions of the EM spectrum in
- Know the main regions of the electromagnetic spectrum in order of frequency and in order of wavelength
3.3.2—All EM waves travel at the same high
- Know: all electromagnetic waves travel at the same high speed in a vacuum
3.3.3—EM spectrum uses: (a) radio waves
- Describe typical EM spectrum uses: (a) radio waves: radio/TV, astronomy, RFID (b) microwaves: satellite TV, mobile phones, microwave ovens (c) infrared: grills, remotes, intruder alarms, thermal imaging, optical fibres (d) visible light: vision, photography, illumination (e) ultraviolet: security marking, fake banknote detection, sterilising water (f) X-rays: medical scans, security scanners (g) gamma rays: sterilising food/medical equipment, cancer detection/treatment
3.3.4—Harm from excessive EM radiation: (a)
- Describe harm from excessive EM radiation: (a) microwaves: internal body-cell heating (b) infrared: skin burns (c) ultraviolet: surface-cell/eye damage, skin cancer and eye conditions (d) X-rays/gamma rays: mutation or cell damage
3.3.5—Communication with artificial
- Know: communication with artificial satellites is mainly by microwaves: (a) some satellite phones use low orbit artificial satellites (b) some satellite phones and direct broadcast satellite television use geostationary satellites
3.3.6—Speed of EM waves in a vacuum is 3.0 ×
- Know: the speed of electromagnetic waves in a vacuum is 3.0 × 108 m/s and is approximately the same in air
3.3.7—EM radiation: (a) mobile
- Know communication systems using EM radiation: (a) mobile phones/wireless internet use microwaves because they penetrate some walls and need short aerials (b) Bluetooth uses radio waves because they pass through walls but weaken (c) optical fibres use visible/infrared for cable TV and high-speed broadband because glass transmits them and they carry high data rates
3.3.8—Difference between a digital and
- Know the difference between a digital and analogue signal
3.3.9—A sound can be transmitted as a
- Know: a sound can be transmitted as a digital or analogue signal
3.3.10—Benefits of digital signalling
- Explain the benefits of digital signalling including increased rate of transmission of data and increased range due to accurate signal regeneration
Topic 3.4
3.4 Sound
Objectives in this topic
3.4.1—Production of sound by vibrating
- Describe the production of sound by vibrating sources
3.4.2—Longitudinal nature of sound waves
- Describe the longitudinal nature of sound waves
3.4.3—Approximate range of frequencies
- State the approximate range of frequencies audible to humans as 20 Hz to 20 000 Hz
3.4.4—A medium is needed to transmit sound
- Know: a medium is needed to transmit sound waves
3.4.5—Speed of sound in air is approximately
- Know: the speed of sound in air is approximately 330–350 m/s
3.4.6—Method involving a measurement of
- Describe a method involving a measurement of distance and time for determining the speed of sound in air
3.4.7—Changes in amplitude and frequency
- Describe how changes in amplitude and frequency affect the loudness and pitch of sound waves
3.4.8—An echo as the reflection of sound
- Describe an echo as the reflection of sound waves
3.4.9—Ultrasound as sound with a frequency
- Define ultrasound as sound with a frequency higher than 20 kHz
3.4.10—Compression and rarefaction
- Describe compression and rarefaction
3.4.11—That, in general, sound travels faster
- Know that, in general, sound travels faster in solids than in liquids and faster in liquids than in gases
3.4.12—Uses of ultrasound in non- destructive
- Describe the uses of ultrasound in non- destructive testing of materials, medical scanning of soft tissue and sonar including calculation of depth or distance from time and wave speed