GCSE Physics B (Triple) OCR

Waves

Wave Basics

• Waves transfer energy from one place to another without transferring matter.
• Wave speed is how quickly the wave is moving. It is measured in metres per second (m/s).
• Wavelength is the distance between each wave, measured from peak to peak or trough to trough.
• Frequency is the number of waves passing a point each second. It's measured in hertz (Hz).
• Amplitude is the maximum extent of a vibration or oscillation, measured from the position of equilibrium.
• The wave equation is v=fλ where v is wave speed, f is frequency, and λ is wavelength.

Types of Waves

• Transverse waves move the material perpendicular to the direction of the wave. Examples include light waves and waves on a string.
• Longitudinal waves move the material parallel to the direction of the wave. Examples include sound waves and ultrasound waves.

Wave Interactions

• When waves meet they can Interfere with each other, with the wave amplitudes adding together.
• Reflection happens when waves bounce back off a surface.
• Waves can be refracted, or change direction, as they enter a different medium.
• Diffraction is the spreading out of waves when they pass through an opening or around a barrier.
• Under certain conditions, waves can constructively interfere to produce a wave with larger amplitude, or destructively interfere to decrease or eliminate the wave amplitude.

Electromagnetic Waves

• Electromagnetic waves include radio waves, microwaves, infrared waves, visible light, ultraviolet radiation, X-rays, and gamma rays.
• They are all transverse waves and they all travel at the same speed - the speed of light (3 x 10^8 m/s) in a vacuum.
• As the frequency of the waves increases, so does their energy. This can make some electromagnetic waves particularly dangerous, such as X-rays and gamma rays.

Sound Waves

• Sound is produced by vibrations and travels as a longitudinal wave.
• The frequency of the vibrations determines the pitch of the sound, and the amplitude determines the loudness.
• Sound can be reflected, causing an echo, refracted as it enters different mediums, or diffracted as it spreads out from its source.
• Humans typically can hear frequencies between 20 and 20,000 Hz.

Waves in the Earth

• P-waves and S-waves are seismic waves created by earthquakes.
• Primary waves (P-waves) are longitudinal waves that can travel through solids and liquids.
• Secondary waves (S-waves) are transverse waves that can only travel through solids.
• Studying these waves can provide valuable information about the structure of the Earth's interior.