physics

Cards (100)

  • Vector
    A quantity that has both a size and a direction
  • absorption spectrum
    A spectrum of light (or electromagnetic radiation) that includes black lines. These are caused by some wavelengths being absorbed by materials that the light (or radiation) passes through
  • acceleration
    A measure of how quickly the velocity of something is changing. It can be positive if the object is speeding up or negative if it is slowing down. It is a vector quanitity.
  • Action - Reaction forces
    Pairs of forces on interacting objects. They are always the same size, in opposite directions, and on acting on different objects.
  • activity
    The number of emissions of ionising radiation from a sample in a given time. This is usually given in becquerels (Bq)
  • alpha particle
    A particle made up of two protons and two neutrons, emitted as ionising radiation from radioactive isotopes.
  • amplitude
    The size of vibrations or the maximum distance a particle moves away from its resting position when a wave passes
  • amplify
    To make bigger
  • angle of incidence
    The angle between an incoming light ray and the normal
  • angle of reflection
    The angle between the normal and a ray of light that has been reflected
  • atom
    The smallest neutral part of an element that can take part in chemical reactions
  • atomic number

    number of protons in the nucleus of an atom
  • average speed
    the speed worked out from the total distance travelled divided by the total time taken for a journey
  • background radiation
    Ionising radiation that is around us all the time from a number of sources. Some of it is naturally occurring, but some comes from human activities
  • balanced forces
    When the forces in opposite directions are the same size so that there is a zero resultant force
  • becquerel (Bq)
    The unit for the activity of a radioactive substance. One Bq = One Radioactive decay per second
  • beta particle
    A particle of radiation emitted from the nucleus of a radioactive atom when it decays. It is a fast moving electron.
  • braking distance
    The distance travelled by a vehicle while the brakes are applied to bring it to a halt
  • centripetal force
    A force that causes objects to follow a circular path. The force acts towards the centre of the circle
  • chain reaction
    The sequence of reactions produced when a nuclear fission reaction triggers one or more fissions
  • cochlea
    The part of the ear that changes vibrations into electrical impulses
  • elastic potential energy
    Stored or stretched energy that can allow an object to change back to its original shape
  • electromagnetic waves

    a group of waves that travel at the same speed in a vacuum (speed of light) and are transverse
  • electrostatic repulsion

    a force between two charges that have the same sign that pushes them apart
  • emission spectrum
    A set of wavelengths of light or electromagnetic radiation showing which wavelengths have been given out by a substance
  • external radiotherapy
    treatment of cancer by sending radiation into the body from the outside
  • focal length
    the distance from a lens to the focal point
  • focal point
    The point at which parallel light rays converge after passing through a converging lens (or spread out in a diverging lens)
  • frequency
    the number of vibrations (or waves) per second measured in Hertz
  • gamma ray
    high frequency, highly penetrating electromagnetic wave emitted from the nucleus of a radioactive atom
  • Geiger-Muller (GM) Tube
    A device that can detect ionising radiation and is used to measure the activity of a radioactive source
  • gravitational field strength
    A measure of how strong the force of gravity is somewhere. The units are newtons per kg (N/kg)
  • half-life
    The average time taken for half of the radioactive nuclei in a sample of radioactive material to have decayed
  • incident ray

    a ray of light going towards an interface or object
  • inertial mass
    Ratio of force divided by acceleration.
  • infrared radiation
    EM radiation that we can feel as heat
  • infrasound
    Sound waves with a frequency below 20 Hz, which is too low for the human ear to detect
  • instantaneous speed
    The speed at one particular moment in a journey
  • interface
    The boundary between two mediums
  • internal radiotherapy
    Treatment of cancer by putting a radioactive source inside the body