CIE Physics A2

A comprehensive set of vocabulary flashcards covering the CIE A-Level Physics syllabus, including gravitation, thermodynamics, medical imaging, quantum physics, and nuclear definitions.

Line of gravitational force

The direction of force on a small test mass.

Gravitational field strength (near Earth’s surface)

Approximately constant because the lines of force are radial, but since the Earth has a large radius, the lines are approximately parallel at the surface.

Potential energy of ideal gas molecules

Zero, because there are no intermolecular forces.

$$\langle c^2 \rangle$$

The mean square speed of molecules.

$$T$$

The thermodynamic temperature.

Thermal energy during melting

Energy required to break bonds between molecules, which increases potential energy while kinetic energy and temperature remain constant.

Simple Harmonic Motion (SHM) conditions

1. Acceleration is proportional to displacement. 2. Displacement and acceleration are in opposite directions.

Bandwidth

The range of frequencies of a signal.

Capacitance of a parallel plate capacitor

The ratio of charge to potential ($C = Q/V$), where charge ($Q$) is on one plate and potential ($V$) is the potential difference between the plates.

Negative feedback

A process where a fraction of the output is returned to the input and subtracted from the input.

Effects of negative feedback

1. Greater bandwidth. 2. Smaller gain.

Magnetic flux linkage

The product of magnetic flux density, cross-sectional area, and the number of turns on a coil ($B \times A \times N$) when the field is normal to the area.

Photoelectric effect

The emission of electrons when electromagnetic radiation is incident on the surface of a material.

Photon

A discrete amount (quantum) of energy of electromagnetic radiation.

CT scanning basic principle

Combining many X-ray images taken from different angles of a single slice to produce a 2D image, then repeating for many slices to build a 3D image.

Newton's law of gravitation

The gravitational force between two point masses is proportional to the product of their masses and inversely proportional to the square of their separation.

Internal energy of a system

The sum of potential and kinetic energies of molecules undergoing random motion.

Internal energy of an ideal gas

Directly proportional to the thermodynamic temperature because there are no intermolecular forces (zero potential energy), making internal energy solely kinetic.

Geostationary orbit direction

West to East.

Geostationary orbit position

Directly above the Equator.

Geostationary communication frequency

A value in the range $(1-300) \times 10^9\,Hz$.

Electric field strength

Force per unit positive charge.

Faraday's law of electromagnetic induction

Induced e.m.f. is proportional to the rate of change of magnetic flux linkage.

Contrast (X-ray image)

The difference in the degrees of blackening between various structures in the image.

Gravitational potential at a point

Work done per unit mass in moving a mass from infinity to that point.

Specific acoustic impedance ($Z$)

The product of the density of a medium and the speed of ultrasound in that medium ($Z = \rho c$).

Acoustic impedance and reflection

If $Z_1 \approx Z_2$, reflection is negligible. If $Z_1$ is very different from $Z_2$, reflection is mostly total.

Electric potential at a point

Work done per unit positive charge in moving the charge from infinity to that point.

Infinite bandwidth (Op-amp)

The gain remains constant for all frequencies.

Infinite slew rate (Op-amp)

No time delay between a change in input voltage and the resulting change in output voltage.

Magnetic field

A region where a force is experienced by a current-carrying conductor, a moving charge, or a permanent magnet.

Radioactive decay

The spontaneous and random release of photons or particles from an unstable nucleus.

Ideal gas

A gas that follows the equation $PV/T = \text{Constant}$, where $T$ is the thermodynamic temperature.

Specific latent heat of fusion

The thermal energy per unit mass required to change a substance from solid to liquid at a constant temperature.

Amplitude modulation (AM)

The amplitude of the carrier wave varies in synchrony with the displacement of the information signal.

Magnetic flux density ($B$)

The force per unit current per unit length on a conductor placed normal to the magnetic field.

Nuclear fusion

A process where two light nuclei combine to form a single, more massive nucleus.

Nuclear fission

A process where a single large nucleus divides to form smaller nuclei of similar size.

First law of thermodynamics ($\Delta U = q + w$)

${+}\Delta U$ is the increase in internal energy, ${+}q$ is the heat energy transferred to the system, and ${+}w$ is the work done on the system.

Binding energy of a nucleus

The minimum work done to separate the nucleons in a nucleus to infinity.

Digital signal

A signal that consists of discrete values, such as 1s and 0s.

ADC (Analogue-to-Digital Converter)

A component that samples an analogue signal at regular intervals and converts it into digital numbers.

Brownian motion observation

Small pollen grains (or smoke particles) moving randomly, providing evidence for the motion of molecules in a fluid.

Hardness (X-ray)

The penetration strength of the X-ray beam, increased by using a greater accelerating potential difference.

Coulomb's law

The electric force between two point charges is proportional to the product of the charges and inversely proportional to the square of their separation.

De Broglie wavelength

The wavelength associated with a moving particle, dependent on its momentum ($\lambda = h/p$).

Radian

The angle subtended at the center of a circle by an arc equal in length to the radius.

Radioactive half-life

The time taken for the number of undecayed nuclei in a sample to be reduced to one half of its original value.

Standard candle

An astronomical object with a known luminosity.

Luminosity

The total power of radiation emitted by a star.

Wien's displacement law

The wavelength of peak intensity is inversely proportional to the thermodynamic temperature.

Decay constant ($\lambda$)

The probability of decay of a nucleus per unit time.

Specific latent heat of vaporisation

The thermal energy per unit mass required to change a substance from liquid to gas at a constant temperature.

Resonance

Oscillations of an object at maximum amplitude when the driving frequency matches the natural frequency of the object.

Tesla ($T$)

Newton per ampere per metre, where the current is perpendicular to the magnetic field.

Root-mean-square (r.m.s.) voltage

The value of a constant (d.c.) voltage that produces the same power as the mean power of the alternating voltage.

Sharpness (X-ray image)

The ease with which the edges of structures can be distinguished.

Work function energy ($\Phi$)

The minimum photon energy required to remove an electron from the surface of a metal.

Redshift

The increase in the observed wavelength of electromagnetic radiation from an object moving away from the observer.

Mass defect

The difference between the total mass of the individual nucleons and the mass of the nucleus when they are bound together.