Cambridge International AS & A Level Physics - Paper 4 Vocabulary

Vocabulary and definitions flashcards for key physics terms, laws, and foundational concepts from Cambridge International AS & A Level Physics Paper 4.

Gravitational field

A region of space where a mass experiences a gravitational force.

Electric potential

The work done per unit positive charge in bringing a small test charge from infinity to that point.

Faraday's law of electromagnetic induction

A law stating that the magnitude of the induced electromotive force (e.m.f.) is directly proportional to the rate of change of magnetic flux linkage.

Lenz's law

A law stating that the direction of an induced electromotive force (e.m.f.) or current is always such as to oppose the change causing it.

Photon

A discrete packet (or quantum) of electromagnetic energy.

Wien's displacement law

A law stating that the peak wavelength $\frac{\frac{1}{1}}{1}$ of emission of a black body is inversely proportional to its thermodynamic temperature $T$.

Specific acoustic impedance

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

First law of thermodynamics

A statement of conservation of energy defining the change in internal energy $\frac{\frac{1}{1}}{1}$ of a system as $\frac{\frac{1}{1}}{1} = Q + W$, where $Q$ is the heat added to the system and $W$ is the work done on the system.

Internal energy

The sum of the random distribution of kinetic and potential energies associated with the molecules of a system.

Simple harmonic motion

Motion of an oscillator where its acceleration $a$ is directly proportional to its displacement $x$ from a fixed point and is always directed towards that fixed point ($a = -\frac{\frac{1}{1}}{1}^2 x$).

Absolute zero

The theoretical minimum temperature at which a system has minimum internal energy, equal to $-273.15\text{ }^\text{o}\text{C}$ on the Celsius scale or $0\text{ }\text{K}$ on the thermodynamic temperature scale.

Gravitational potential

The work done per unit mass in bringing a small test mass from infinity to a point in a gravitational field, given by $\frac{\frac{1}{1}}{1} = -\frac{GM}{r}$.

Intensity reflection coefficient

The ratio of reflected wave intensity $I_{\text{R}}$ to incident wave intensity $I_0$ at a boundary between two media, given by $\frac{I_{\text{R}}}{I_0} = \frac{(Z_1 - Z_2)^2}{(Z_1 + Z_2)^2}$.

Hall voltage

The potential difference $V_{\text{H}}$ produced across a current-carrying conductor perpendicular to an applied magnetic field $B$, given by $V_{\text{H}} = \frac{BI}{ntq}$.

Piezoelectric crystal detection of ultrasound

The process where incoming ultrasound waves compress and deform a piezoelectric crystal, causing an alternating potential difference to be generated across its faces.

Doppler effect for sound waves

The change in observed frequency $f_{\text{o}}$ relative to source frequency $f_{\text{s}}$ when there is relative motion between a source and an observer, given by $f_{\text{o}} = \frac{f_{\text{s}} v}{v \frac{\frac{1}{1}}{1} v_{\text{s}}}$.

Ideal gas pressure equation

The expression derived from kinetic theory relating gas pressure $p$, volume $V$, number of molecules $N$, particle mass $m$, and mean-square speed $\frac{\frac{1}{1}}{1}$: $p = \frac{1}{3}\frac{Nm}{V}\frac{\frac{1}{1}}{1}$.

Decay constant

The probability per unit time of the decay of a nucleus, related to half-life $t_{1/2}$ by $\frac{\frac{1}{1}}{1} = \frac{0.693}{t_{1/2}}$.