UG008982 � Specification � Edexcel GCSE in Science: Single, Double, Separate Sciences B � 47

use the following units:

� coulomb (C), ampere (A), volt (V), power (W), second (s), metre (m), hertz (Hz), metre per second (m/s), newton (N), newton metre (Nm) (12.01)

describe common materials which are electrical conductors or insulators including metals and plastics (12.02)

describe how an insulator can be charged by friction, resulting in the transfer of electrons (12.03)

recall that like charges repel and unlike charges attract (12.04)

describe common electrostatic phenomena in terms of movement of electrons, for example

describe some of the uses and dangers of electrostatic charges in everyday situations, eg fuelling aircraft and tankers, photocopiers and inkjet printers (12.06)

explain how earthing removes the excess charge on a body, with reference to the movement of electrons (12.07)

understand that current is rate of flow of charge (12.08)

recall and use the equation

� charge (C) = current (A) ﾗ time (s)

Q = I ﾗ t (12.09)

understand that electric current in metals is a flow of negatively charged electrons (12.10)

understand that electric current in molten or dissolved electrolytes is a movement of both positive and negative ions (12.11)

recall and use the equation

� electrical power (W) = current (A) ﾗ voltage (V)

P = I ﾗ V (12.12)

use the quantitative relationship between energy transferred, current, voltage and time

� energy transferred = current ﾗ voltage ﾗ time

E = I ﾗ V ﾗ t

understand that voltage is the energy transferred per unit charge passed; the volt as a joule per coulomb (12.14)

recall that a force is exerted on a current-carrying wire in a magnetic field and understand how this is used in a simple d.c. motor (12.15)

understand that when a wire carrying a current is perpendicular to a magnetic field, the resulting force is perpendicular to both (12.16)

recall the structure of a transformer and understand that a transformer changes the size of an alternating voltage by having different numbers of turns on the input and output sides (12.17)

recall and use the quantitative relationship between input (primary) and output (secondary) voltages and the turns ratio for a transformer

Voltage (primary)          =        turns (primary)

Voltage (secondary)      =        turns (secondary)

explain the use of step-up and step-down transformers in transmitting electricity (12.19)

understand that transmitting electrical power at high voltages reduces the current required, and this reduces power losses caused by heating (12.20)

recall that waves transfer energy and information without transferring matter (12.21)

recall and use the equation for all waves:

- wave speed (m/s) = frequency (Hz) ﾗ wavelength (m)

v = f ﾗ . (12.22)

understand the condition for total internal reflection to take place and how this is used in optical fibres and in reflecting prisms (12.23)

understand that digital signals can carry more information than analogue signals

recall that waves spread out when they pass through a narrow gap or past an edge and that this is called diffraction (12.25)

understand that sound and light show diffraction effects (12.26)

describe and interpret some examples of diffraction, eg

understand how reflection and diffraction affect the quality of received radio signals (12.28)

Candidates following the Welsh National Curriculum should be taught the principle of moments and its application to situations involving one pivot in order to meet statutory requirements.

understand that the upward forces on a light beam supported at its ends vary with the position of a heavy object placed on the beam (12.29)

describe how extension varies with applied force for a range of materials including springs and rubber bands (12.30)

recall that particles in a gas have random motion and that they exert a force on the walls of the container (12.31)

understand the relationship between the pressure and volume of a fixed mass of gas at constant temperature and use the quantitative relationship

� P1 ﾗ V1 = P2 ﾗ V2 (12.32)