A'Level Physics: Oscillations, Waves, and Modern Physics

These vocabulary flashcards cover essential concepts from A-Level Physics units including SHM, waves, sound, light, radioactivity, medical imaging, digital technology, and particle physics based on the provided lecture transcript.

Oscillation

A complete to-and-fro movement of a body on either side of an equilibrium position.

Period ($T$)

The time taken for one complete oscillation, measured in seconds ($s$).

Frequency ($f$)

The number of complete oscillations per unit time, measured in Hertz ($Hz$), where $f = \frac{1}{T}$.

Amplitude ($A$)

The maximum displacement of an oscillating body from its equilibrium position.

Phase

The point that an oscillating mass has reached within its complete cycle.

Simple Harmonic Motion (SHM)

A periodic motion of a particle about a fixed point such that its acceleration $a$ is directly proportional to its displacement $x$ from the fixed point and is directed towards that fixed point ($a = -\omega^2 x$).

Angular Frequency ($\omega$)

The rate of change of phase angle, related to frequency by $\omega = 2\pi f$, measured in $rad\,s^{-1}$.

Free Oscillations

Oscillations that occur in the absence of any external dissipative forces, maintaining constant amplitude.

Damping

The process by which resistive forces dissipate the energy of a vibrating system, causing the amplitude to decrease with time.

Critical Damping

A type of damping where the displacement is reduced to zero in the shortest possible time without any oscillation.

Forced Oscillations

Oscillations that occur when a system is subjected to an external periodic force, making it vibrate at the frequency of the external force.

Resonance

A phenomenon occurring when the natural frequency of vibration of a system is equal to the driving frequency, result in maximum amplitude of vibration.

Transverse Wave

A wave in which the particles of the medium vibrate perpendicular to the direction of wave propagation (e.g., light waves).

Longitudinal Wave

A wave in which the particles vibrate parallel to the direction of propagation (e.g., sound waves).

Wavelength ($\lambda$)

The distance between two successive identical points on a wave that are in phase, such as the distance between two successive crests.

Wavefront

An imaginary line or surface joining points that are in phase within a wave.

Progressive Wave

A wave that transfers energy from one point to another without the transfer of matter.

Superposition Principle

The principle stating that when two waves overlap, the resultant displacement at any point is the algebraic sum of the individual displacements.

Stationary Wave

A wave formed by the superposition of two progressive waves of the same speed, amplitude, and frequency moving in opposite directions.

Nodes

Points on a stationary wave where the particles are permanently at rest (zero displacement).

Antinodes

Positions on a stationary wave where particles vibrate with maximum amplitude.

Coherent Sources

Sources of waves that have the same frequency and maintain a constant phase relationship.

Interference

The overlapping of waves from coherent sources resulting in regions of maximum and minimum intensity.

Diffraction

The spreading of a wave into its geometrical shadows after passing through a narrow slit or around an edge.

Polarization

The process of confining the vibrations of the electric field vector of a transverse wave to a single plane.

Refraction

The change in direction of a wave due to a change in its speed as it passes from one medium to another.

Intensity of Sound

The rate of flow of energy per unit area perpendicular to the direction of travel, proportional to the square of the amplitude ($I \propto a^2$).

Beats

Periodic rises and falls in sound intensity produced when two notes of nearly equal frequency are sounded together.

Doppler Effect

The apparent change in the frequency of a wave due to the relative motion between the source and the observer.

Fundamental Note

The lowest frequency note produced by a vibrating string or air column.

Harmonic

A note whose frequency is a simple whole number multiple of the fundamental frequency.

Overtones

Notes of higher frequency than the fundamental note produced by an instrument.

Photon

A quantum or packet of energy of electromagnetic radiation, with energy $E = hf$.

Photoelectric Effect

The emission of electrons from a metal surface when it is irradiated with electromagnetic radiation of sufficiently high frequency.

Work Function ($W_0$)

The minimum amount of energy required to liberate an electron from the surface of a metal.

Threshold Frequency ($f_0$)

The minimum frequency of incident radiation below which photoelectric emission cannot occur.

Stopping Potential ($V_s$)

The minimum negative potential applied to the anode of a photocell to reduce the photocurrent to zero, measuring maximum kinetic energy ($KE_{max} = eV_s$).

Compton Effect

The scattering of short-wavelength photons (X-rays) by electrons, resulting in a loss of energy and a corresponding increase in wavelength.

Laser

Light Amplification by Stimulated Emission of Radiation; a device producing a narrow, intense, monochromatic, and coherent beam of light.

Stimulated Emission

A process where an incident photon causes an excited electron to drop to a lower energy state, emitting a second photon identical to the first.

X-rays

Short-wavelength electromagnetic radiations produced when fast-moving electrons are rapidly decelerated by a metal target.

Absorbed Dose

The radiation energy absorbed per unit mass of a medium, measured in grays ($Gy$), where $1\,Gy = 1\,J\,kg^{-1}$.

Effective Half-life

The time required to reduce the radioactivity level of an organ to half its original value, accounting for both radioactive decay and biological clearance.

Albedo

The fraction of incident solar radiation that is reflected back into space by the surface of a planet.

Black Body

An ideal body that absorbs all electromagnetic radiation falling on it, reflecting and transmitting none.

Stefan-Boltzmann Law

The power radiated by a black body is proportional to the fourth power of its thermodynamic temperature ($P = \sigma AT^{4}$).

Greenhouse Effect

A natural process where atmospheric gases trap long-wave radiation from the Earth's surface, warming the planet.

Mechanical Weathering

The physical breakdown of rocks into smaller pieces through physical forces like thermal expansion and ice wedging.

Earthquake

The shaking of the Earth's surface caused by the sudden release of energy accumulated in rocks beneath the crust.

Isotopes

Atoms of the same element that contain the same number of protons but different numbers of neutrons.

Mass Defect

The difference between the total mass of individual separate nucleons and the combined mass of the resulting stable nucleus.

Binding Energy

The minimum energy required to completely separate the nucleons of a nucleus to infinity.

Nuclear Fission

The splitting of a heavy nucleus into two lighter nuclei of approximately same mass, accompanied by energy release.

Nuclear Fusion

The union of two very light nuclei to form a heavier, more stable nucleus with a higher binding energy per nucleon.

Decay Constant ($\lambda$)

The probability of radioactive decay of a nucleus per unit time.

Analogue Signal

An information signal in which current or voltage varies continuously and smoothly with time.

Digital Signal

A signal consisting of a sequence of discrete voltage pulses, representing binary ones ($1$) and zeros ($0$).

Handover

The process in a cellular network where a call is automatically transferred from one radio channel to another as a mobile user crosses cell boundaries.

Modulation

The process of superimposing a low-frequency information signal onto a high-frequency carrier wave signal.

Bandwidth

The range of frequencies occupied by a signal, defined as the difference between the highest and lowest frequencies present.

Inertial Reference Frame

A reference frame in which Newton's first law of motion (the law of inertia) holds true.

Quarks

Fundamental particles that carry fractional electric charges and form the building blocks of hadrons like protons and neutrons.

Leptons

Elementary particles, such as electrons and neutrinos, that do not experience the strong nuclear force.

Hadrons

Composite particles made of quarks, including baryons (three quarks) and mesons (quark-antiquark pair).

Pauli Exclusion Principle

The principle stating that no two identical fermions in a system can occupy the same quantum state simultaneously.

Heisenberg Uncertainty Principle

The principle stating that we cannot precisely measure certain pairs of properties, such as energy and time, simultaneously ($\Delta E\Delta t \geq \frac{h}{4\pi}$).