GTLE Subject Specialism Physics flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Newton's second law

The net force on an object equals its mass multiplied by its acceleration, F = ma. Acceleration is always in the direction of the net force, not necessarily the direction of motion.

Centripetal acceleration

For an object moving in a circle of radius r at speed v, the centripetal acceleration is v squared divided by r, directed toward the centre. A net inward force is required.

Conservation of momentum

In a system with no external net force, total momentum before a collision equals total momentum after. This holds for both elastic and inelastic collisions, unlike kinetic energy.

Elastic potential energy

Energy stored in a stretched or compressed spring obeying Hooke's law, given by one half times the spring constant times the extension squared. Valid only within the elastic limit.

Snell's law

When light crosses a boundary, n one times sine theta one equals n two times sine theta two, where n is refractive index and angles are measured from the normal.

Critical angle

The angle of incidence above which total internal reflection occurs when light travels from a denser to a less dense medium. Its sine equals the ratio of refractive indices.

Doppler effect

The observed frequency of a wave is higher than the emitted frequency when source and observer approach, and lower when they recede, because relative motion changes the effective wavelength.

Decibel scale

Sound intensity level equals ten times the logarithm base ten of intensity divided by the reference intensity one times ten to the minus twelve watts per square metre.

Ohm's law

For an ohmic conductor at constant temperature, current is directly proportional to potential difference, so V = IR. The resistance R is constant and independent of current.

Faraday's law

The induced emf in a circuit equals the rate of change of magnetic flux linkage. Faster changes, stronger fields, or more turns give a larger induced emf.

Lenz's law

The direction of an induced current is such that it opposes the change in magnetic flux that produced it. This is a consequence of energy conservation.

Kirchhoff's laws

Current entering a junction equals current leaving it, expressing charge conservation. Around any closed loop, the sum of emfs equals the sum of potential differences, expressing energy conservation.

Ideal transformer

Voltage ratio equals turns ratio, so secondary voltage over primary voltage equals secondary turns over primary turns. An ideal transformer conserves power, so primary and secondary power are equal.

Specific latent heat

The energy required to change the phase of one kilogram of a substance without changing its temperature, given by Q = mL. It differs for melting and for vaporisation.

Ideal gas law

For an ideal gas, pressure times volume equals the number of moles times the gas constant times absolute temperature. Temperature must be expressed in kelvin.

Kinetic theory pressure

Gas pressure arises from molecular collisions with the container walls. Raising temperature increases mean molecular speed, so collisions become more frequent and more forceful.

First law of thermodynamics

The change in internal energy of a system equals heat added to the system minus work done by the system. Sign conventions must be stated explicitly when applying it.

Photoelectric effect

Light above a threshold frequency ejects electrons from a metal surface. Maximum kinetic energy equals photon energy minus work function, and intensity affects only the number emitted.

de Broglie wavelength

Every particle has an associated wavelength equal to Planck's constant divided by its momentum. Electron diffraction experiments confirm this wave behaviour for matter.

Half-life

The time for half the nuclei in a sample to decay, or for activity to halve. After n half-lives the remaining fraction is one half raised to the power n.

Binding energy per nucleon

The energy released when a nucleus forms, divided by its nucleon number. It peaks near iron-56, so fusion releases energy for light nuclei and fission for heavy ones.

Percentage uncertainty

The absolute uncertainty divided by the measured value, multiplied by one hundred. For products and quotients, percentage uncertainties add; for sums, absolute uncertainties add.

Random versus systematic error

Random errors scatter readings about a true value and are reduced by averaging repeats. Systematic errors shift all readings the same way and require calibration or zero correction.

Micrometer and vernier precision

A vernier calliper typically reads to 0.1 millimetres and a micrometer to 0.01 millimetres. Always check for zero error before taking measurements.

Laser safety rule

Never look directly into a laser beam or its specular reflection. Use beam stops, keep the beam below eye level, and use the lowest class adequate for the demonstration.

Writing learning objectives

Objectives should state observable outcomes using verbs such as calculate, describe, explain, or predict, and should match exactly what the assessment will ask students to do.

Spiral curriculum sequencing

Core ideas such as energy, forces, and waves are revisited at increasing depth across year groups, rather than being taught once and abandoned after the topic test.

Planning practical work

A practical plan states the aim, identifies independent, dependent, and control variables, and describes how extraneous variables will be held constant and how repeats will be taken.

Force and motion misconception

A common misconception is that a continuous force is needed to keep an object moving. In fact, a net force changes motion; constant velocity requires zero net force.

Current in parallel circuits

Students often think current is shared equally between parallel branches. In fact the voltage is equal across branches and current divides inversely with branch resistance.

Heat and temperature confusion

Temperature measures mean molecular kinetic energy, while heat is energy transferred due to a temperature difference. They are distinct quantities with different units.

Velocity-time graph gradient

The gradient of a velocity-time graph gives acceleration, and the area under the line gives displacement. A horizontal line means constant velocity and zero acceleration.

Gradient and area meaning

On any straight-line physics graph, the gradient equals the constant rate of change of the y quantity with respect to x, and the area under the line equals the product of the axes.