| A progressive wave transfers energy without transferring material and is made up of particles of a medium (or field) oscillating. For example, water waves are made of water particles moving up and down. | Progressive Wave |
| What is the amplitude of a wave? | The amplitude is a wave’s maximum displacement from the equilibrium position (units are m). |
| The frequency, f is the number of complete oscillations passing through a point per second (units are Hz). | Frequency, f |
| What does the wavelength, λ of a wave represent? | The wavelength, λ is the length of one whole oscillation (e.g., the distance between successive peaks or troughs) (units are m). |
| The speed, c is the distance traveled by the wave per unit time (units are m/s). | Speed, c |
| What is phase in the context of a wave? | Phase is the position of a certain point on a wave cycle (units are radians, degrees, or fractions of a cycle). |
| Phase difference describes how much a particle or wave lags behind another particle or wave (units are radians, degrees, or fractions of a cycle). | Phase Difference |
| What does the period, T of a wave measure? | The period, T is the time taken for one full oscillation (units are s). |
| Two points are in phase if they are at the same point in the wave cycle, with the same displacement, velocity, and a phase difference of a multiple of 360° (or 2π radians). | In Phase |
| What must two points have to be in phase? | Same displacement, velocity, frequency, and wavelength (not amplitude). |
| Two points are completely out of phase when they are an odd integer of half cycles apart, e.g. 5 half cycles apart (1 half cycle = 180° or π radians). | Completely Out of Phase |
| When are two points completely out of phase? | When they are an odd integer of half cycles apart, e.g., 180° apart. |
| The speed of a wave is equal to its frequency multiplied by its wavelength: c = fλ | Wave Speed Equation |
| What is the formula for wave speed? | c = fλ |
| The frequency of a wave is equal to 1 divided by its period:f = 1/T | Frequency and Period |
| How is frequency related to the period of a wave? | f = 1/T |
| In transverse waves, the oscillation of particles (or fields) is at right angles to the direction of energy transfer. | Transverse Waves |
| What kind of waves are all electromagnetic (EM) waves, and what is their speed in a vacuum? | EM waves are transverse and travel at 3 x 10⁸ m/s in a vacuum. |
| Transverse waves can be demonstrated by shaking a slinky vertically or through waves on a string attached to a signal generator. | Demonstrating Transverse Waves |
| In which direction do particles oscillate in longitudinal waves? | In longitudinal waves, particles oscillate parallel to the direction of energy transfer. |
| Longitudinal waves are made up of compressions and rarefactions and cannot travel in a vacuum. | Longitudinal Waves |
| Give an example of a longitudinal wave and how it can be demonstrated. | Sound is an example of a longitudinal wave, and it can be demonstrated by pushing a slinky horizontally. |
| A polarised wave oscillates in only one plane (e.g., only up and down). Only transverse waves can be polarised. | Polarised Wave |
| What evidence does polarisation provide for the nature of transverse waves? | Polarisation shows that transverse waves oscillate perpendicular to their direction of travel, as only transverse waves can be polarised. |
| Polaroid sunglasses reduce glare by blocking partially polarised light reflected from water and tarmac. They only allow oscillations in the plane of the filter | Polaroid Sunglasses |
| How are TV and radio signals related to polarisation? | TV and radio signals are usually plane-polarised by the orientation of the rods on the transmitting aerial. The receiving aerial must be aligned in the same plane to receive the signal at full strength. |
| Combining the displacements of two waves, with the resultant displacement being the vector sum of each wave’s displacement. | Superposition |
| What is superposition? | The combination of two waves' displacements to form a resultant displacement. |
| Occurs when two waves have displacements in the same direction, resulting in a larger wave. | Constructive Interference |
| When does constructive interference happen? | When two waves have displacements in the same direction. |
| Happens when one wave has positive displacement and the other has negative. Equal and opposite displacements cause total cancellation. | Destructive Interference |
| What is destructive interference? | When one wave's displacement is positive and the other's is negative. If equal, total cancellation occurs. |
| Formed by two progressive waves moving in opposite directions with the same frequency, wavelength, and amplitude. | Stationary Wave |
| How does a stationary wave form? | By two progressive waves moving in opposite directions with the same frequency, wavelength, and amplitude. |
| No energy is transferred by a stationary wave. | Energy Transfer in Stationary Waves |
| Is energy transferred by a stationary wave? | No, energy is not transferred by a stationary wave. |
| Formed where the waves meet in phase during constructive interference, resulting in regions of maximum amplitude. | Antinodes |
| Where are antinodes formed in a stationary wave? | Antinodes are formed where the waves meet in phase, resulting in regions of maximum amplitude. |
| Formed where the waves meet completely out of phase during destructive interference, resulting in regions of no displacement. | Nodes |
| What are nodes in a stationary wave? | Nodes are regions of no displacement formed where the waves meet completely out of phase during destructive interference. |
| Occurs when a wave traveling down a string is reflected at the fixed end and travels back, causing superposition of the waves. If the waves have the same wavelength, frequency, and amplitude, a stationary wave is formed. | Formation of a Stationary Wave |
| How is a stationary wave formed on a string? | A stationary wave is formed when a wave traveling down a string is reflected at the fixed end and travels back, causing superposition of the waves with the same wavelength, frequency, and amplitude. |
| The lowest frequency at which a stationary wave forms, with two nodes and a single antinode. The distance between adjacent nodes (or antinodes) is half a wavelength. | First Harmonic |
| What is the first harmonic in a stationary wave? | The lowest frequency with two nodes and a single antinode, where the distance between adjacent nodes (or antinodes) is half a wavelength. |
| The formula for calculating frequency is: where L is the length of the string, T is the tension, and μ is the mass per unit length. | Frequency Calculation |
| For the nth harmonic, the frequency is n times the first harmonic frequency, with n antinodes. | Harmonics |
| How do you find the frequency of the nth harmonic? | Multiply the first harmonic frequency by n, where n represents the number of antinodes. |
| Formed by reflecting a microwave beam at a metal plate. Nodes and antinodes can be detected using a microwave probe. | Stationary Microwaves |
| How can stationary microwaves be detected? | By reflecting a microwave beam at a metal plate and using a microwave probe to find the nodes and antinodes. |
| Formed by placing a speaker at one end of a closed glass tube. Powder laid across the bottom will shake at the antinodes and settle at the nodes. | Stationary Sound Waves |
| How can you observe stationary sound waves in a closed tube? | By placing a speaker at one end of the tube, laying powder across the bottom, and observing that the powder shakes at the antinodes and settles at the nodes. |
| The distance between nodes is half a wavelength. The frequency of the signal generator and the speed of sound can be found using the formula c=fλ, where c is the speed of sound, f is the frequency, and λ, is the wavelength. | Wavelength and Speed of Sound Calculation |
| How can the speed of sound be calculated using stationary sound waves? | By measuring the distance between nodes (which is half a wavelength), and using the formula c=fλ,, where c is the speed of sound, f is the frequency, and λ is the wavelength. |
