You should be able to (higher tier in bold):
12.01 use the following
units:
– coulomb (C), ampere (A), volt
(V), watt (W), second (s), metre (m), hertz (Hz), metre per
second (m/s), newton (N), newton metre (Nm) ()
Charge and energy
You should be able to (higher tier in bold):
12.02 describe common materials
which are electrical conductors or insulators including metals and
plastics
12.03 describe how an insulator can be charged by friction, resulting in the
transfer of electrons
12.04 recall that like charges repel and unlike charges attract
12.05 describe
common electrostatic phenomena in terms of movement of electrons, for example
– shocks from car doors
– charges on synthetic fabrics
– lightning
12.06 describe some of the uses and
dangers of electrostatic charges in everyday situations, eg fuelling
aircraft and tankers, photocopiers and inkjet printers
12.07 explain how earthing removes the excess charge on a body, with
reference to the movement
of electrons
12.08 understand that current is rate of flow of charge
12.09 recall and use the equation
– charge (C) = current (A) *
time (s)
Q = I * t
12.10 understand that electric current in metals is a flow of negatively
charged electrons
12.11 understand that electric current in molten or dissolved electrolytes is a
movement of both
positive and negative ions
12.12 recall and use the equation
– electrical power (W) = current
(A) * voltage
(V)
P = I * V
12.13 use the quantitative relationship between energy transferred, current,
voltage and time
– energy transferred = current *
voltage *
time
E = I * V
* t
(will be provided if needed)
12.14 understand that voltage is the energy transferred per unit charge passed;
the volt as a joule per
coulomb
12.15 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
12.16 understand that when a wire carrying a current is perpendicular to a
magnetic field, the resulting force
is perpendicular to both
12.17 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
12.18 recall and use the
quantitative relationship between input (primary) and output (secondary)
voltages and the turns ratio for a transformer
voltage (primary) / voltage(secondary) = turns(primary) / turns(secondary
Vp/Vs = np/ns
12.19 explain the use of
step-up and step-down transformers in transmitting electricity
12.20 understand that transmitting electrical power at high voltages reduces the
current required, and this reduces
power losses caused by heating
Waves and communication
You should be able to (higher tier in bold):
12.21 recall that waves transfer
energy and information without transferring matter
12.22 recall and use the
equation for all waves:
- wave speed (m/s) = frequency (Hz) *
wavelength (m)
v = f *l
12.23 understand the
condition for total internal reflection to take place and how this is used in
optical fibres and in reflecting prisms
12.24 understand that digital signals can carry more information than
analogue signals
12.25 recall that waves spread out when they pass through a narrow gap or
past an edge and that this is
called diffraction
12.26 understand that sound and light show diffraction effects
12.27
describe and interpret some examples of diffraction, eg
– of sound by large
building/doorways
– of water waves by harbours
– of light by a single narrow
slit
12.28 understand how reflection and diffraction affect the quality of received
radio signals
Forces and shape
You should be able to (higher tier in bold):
12.29 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
12.30 describe how extension varies with applied force for a range of materials
including springs and rubber bands
12.31 recall that particles in a gas have random motion and that they exert a
force on the walls of the container
12.32 understand the relationship between the pressure and volume of a fixed
mass of gas at constant
temperature and use the quantitative relationship
– P1 *
V1 = P2 * V2
()