Waves Flashcards
What is an Absorption Spectrum?
The frequencies at which a certain element absorbs photons at a higher rate as these frequencies correspond to the spacings between energy levels in the element’s atoms.
Define Amplitude
The maximum displacement of a vibrating particle or wave from its equilibrium, measured in metres.
What is the Angle of Incidence?
The angle at which a light ray hits a medium, measured from a Normal line to the surface of the medium.
Define the Angle of Reflection.
The angle at which a light ray reflects off a surface, measured from a Normal line to the surface of the medium.
What is the Angle of Refraction?
The angle at which light rays travel after transferring into a different refractive index material, measured from a normal line to the surface of the medium.
What is an Antinode?
The point on a stationary wave where the incoming and reflected wave are in phase forming a maximum point.
Define Coherence.
Waves with the same frequency and constant phase difference.
What is Constructive Interference?
Interference when the two waves meet in phase, resulting in larger amplitudes.
What is a Converging Lens?
A lens that takes a parallel set of light rays and causes them to meet at a point.
Define Critical Angle.
The angle of incidence above which total internal reflection occurs.
What does the De Broglie Hypothesis state?
All particles have a wave-like nature and a particle-like nature; the wavelength is inversely proportional to momentum.
What is De-excitation?
The movement of an electron from a high energy level to a lower energy level, causing photons to be released.
Define Destructive Interference.
Interference when the two waves meet antiphase, resulting in a minimum point.
What is Diffraction?
The spreading out of a wave as it passes through a gap or over an edge.
What is Displacement in wave motion?
The distance and direction that a vibrating particle or wave has travelled from its equilibrium position.
What is a Diverging Lens?
A lens that takes a parallel set of light rays and causes them to travel away from each other.
Define Electronvolt.
The kinetic energy gained by one electron that is accelerated through a potential difference of 1 volt, equal to 1.6x10^-19 J.
What is an Emission Spectrum?
The frequencies of photons emitted when atoms de-excite, and electrons move from a high energy level to a lower energy level.
What does Excitation refer to in atomic physics?
The movement of an electron from a low energy level to a higher energy level due to energy transfer.
Define Focal Length.
The distance between the optical centre of the lens and the focal point.
What is a Focal Point?
The point where parallel rays of light meet, or appear to diverge from, after passing through the lens.
Define frequency
The number of complete oscillations of a wave per second, measured in Hz
Define Fundamental Frequency.
The lowest possible frequency for an object, where there is only a single antinode.
What is Huygen’s Principle?
Every point on a wavefront can be treated as a point source of a secondary wavelet.
What is Ionisation?
When an electron is removed from an atom, giving the atom a positive charge.
Fill in the blank: In-Antiphase refers to a phase difference of _______.
180 degrees or π radians.
Fill in the blank: In-Phase refers to a phase difference of _______.
0 degrees or 0 radians.
What is Intensity in the context of waves?
The power transferred by a wave per unit area.
Define Lens Power.
The inverse of the focal length, measured in dioptres D or m-1
What is a Longitudinal Wave?
A wave whose oscillations are parallel to the direction of propagation (e.g., sound waves).
What is Magnification?
The height of an object divided by the height of its image.
What is a Node in wave physics?
The point on a stationary wave where the incoming and reflected wave are in antiphase forming a minimum point.
What is Path Difference?
The difference in the length travelled by two waves arriving at the same point.
Define Time Period
The time taken for a wave to complete oscillation, measured in seconds
Define phase of an oscillation
refers to the position within a cycle that the particle occupies realtive to the onset of the cycle.
What is Phase Difference?
The difference in phase if the phase of two waves is determined at a single point in time.
Define Photoelectric Effect.
When light of high enough energy causes electrons to be emitted from a metal surface.
What is a Plane Polarised Wave?
A wave whose oscillations have been restricted to a single plane.
What is the Principal Axis of a lens?
A line passing through the optical centre of the lens.
What is a Progressive Wave?
A wave that transfers energy from one point to another.
What is the Pulse-Echo Technique?
An ultrasound technique used for imaging by sending short pulses through a medium and recording reflections.
Define Real Image.
Where rays of light have actually converged to produce an image that can be projected onto a screen.
What is Refraction?
When a wave changes speed when it crosses the boundary into a new medium.
Define Refractive Index.
A measure of how much the speed of light changes between two different media.
What does Snell’s Law describe?
The relationship between the angles of incidence and refraction and the refractive indices of the two media.
What is a Stationary Wave?
A wave that stores energy instead of transferring it, formed by two progressive waves of equal frequency and amplitude moving in opposite directions.
Define Superposition.
When two waves meet at the same point, their displacements combine.
What is the Threshold Frequency?
The minimum frequency of light needed to cause electrons to be emitted in the photoelectric effect.
What is Total Internal Reflection?
When the angle of incidence is greater than the critical angle, causing the ray to reflect within the medium.
Define Transverse Wave.
A wave whose oscillations are perpendicular to the wave’s direction of propagation (e.g., electromagnetic waves).
What are Ultrasound waves?
Sound waves with a frequency greater than 20 kHz.
What is a Virtual Image?
An image where rays of light appear to converge but cannot be projected onto a screen.
Define Wavefront.
a line, or surface, in a wave, along which all the points are in phase
What is Wavelength?
The distance between two identical points on a wave, typically measured peak to peak or trough to trough.
What is Wave Speed?
The distance travelled by a wave per second, equal to the product of frequency and wavelength.
Define Work Function.
The minimum energy required to just liberate an electron from the surface of a metal.
Define intensity of radiation
The power per unit area of radiation falling on to a surface
What is the law of reflection
angle of incidence = angle of reflection
What is the optical centre of a lens?
the point through which rays of light will pass without deviation
What does the word quantum mean?
A fixed or discrete amount of energy, E=hf
Define wave-particle duality
Particles can sometime behave like waves and waves can sometime behave like particles.
