Physics, in plain words
Plain-language definitions of school Physics terms, A to Z, each with an example, where marks go, and the board's own source.
26 terms
Terms starting with A
Terms starting with C
Terms starting with D
Terms starting with E
Terms starting with F
Terms starting with H
Terms starting with J
Terms starting with L
Terms starting with M
- Magnetic field linesMagnetic field lines are the lines drawn around a magnet or a current-carrying wire to show the direction and strength of its magnetic field.
- MagnificationMagnification, m, is the height of the image divided by the height of the object, and its sign tells you whether the image is upright or inverted.
- Mirror formulaThe mirror formula, 1/v + 1/u = 1/f, links the object distance, the image distance and the focal length of a spherical mirror.
- Myopia (near-sightedness)Myopia, also called near-sightedness or short sight, is an eye defect in which near objects look clear but distant objects look blurred.
Terms starting with N
Terms starting with O
Terms starting with P
- Power of a lensThe power of a lens is 1 divided by its focal length in metres, measured in dioptres, and shows how strongly the lens bends light.
- Power of accommodationThe power of accommodation is the eye lens's ability to change its focal length, thickening or thinning, so the eye sees both near and far objects clearly.
Terms starting with R
- Refractive indexThe refractive index of a medium compares the speed of light in air or vacuum with its speed in that medium, and so shows how much light bends there.
- ResistivityResistivity is the resistance of a piece of material with unit length and unit area of cross-section, and it depends on the material, not the wire's length or thickness.
- Resistors in parallelResistors are in parallel when they are joined between the same two points, so each has the same potential difference across it.
- Resistors in seriesResistors are in series when they are joined end to end, so the same current flows through each one and their resistances add up.
- Right-hand thumb ruleThe right-hand thumb rule finds the direction of the magnetic field around a current-carrying wire: thumb along the current, fingers curl along the field.
Terms starting with S
- Scattering of lightScattering is the spreading of light in many directions when it strikes tiny particles, such as dust, smoke, water droplets or molecules of air.
- Snell's law of refractionSnell's law says that when light passes from one medium into another, sin i divided by sin r stays constant for a given colour and pair of media.
- SolenoidA solenoid is a long, tightly wound coil of insulated copper wire, shaped like a tube, that behaves like a bar magnet while current flows through it.