ELECTRICITY
Electrostatics
1 Yr
8 Objects
can become charged
due to friction. The cause
of negative or positive charge is the transfer of
electrons
to or from insulators. Repulsion
between charged bodies is a result of the interaction of
like charges. Attraction
between charged bodies is a result of the interaction of
unlike charges. § Electrostatics
2 Yr
10 Flow of
electrons between unbalanced charged objects, limited
to (i)
lightning (ii)
'static' sparks
on clothing The
dangers of movement of electrons between objects with
unbalanced charges, limited to (i) high
voltage cables (ii)
electric
shock (iii)
ignition of flammable vapours § Using
electrostatic charge Yr
10 1. The
action of a photocopier & inkjet printer explained in
terms of forces between charged bodies. § Current Yr
10 1. An
electric
current
is a flow of electrons or ions 2.
Distinction between a.c.
& d.c. 3.
Electrolysis:
positive ions
to cathode,
negative ions to anode. 4. An
ammeter
is used to measure current in series and parallel
circuits 5. An
ammeter must be in series with components in a
circuit. 6. The
unit of electric current (I) is the ampere
(A) The
coulomb (C) is the unit of electric charge
(Q) Electric
current defined as rate of charge transfer (You will
have to remeber and use this quantitative
relationship) Voltage Yr
10 1. A
voltmeter is used to measure potential
difference
(i.e. voltage) in series and parallel circuits. 2. A
voltmeter must be used in parallel
with a component in a circuit. 3. Using a
CRO
to measure a.c. & d.c. frequency
and voltage. 4. The
unit of potential difference (p.d.) is the volt
(V) Voltage
is the energy transferred per unit charge The volt
is defined by this equation: (You will
have to remeber and use this quantitative
relationship) Circuits Yr
10 In an
electrical
circuit
electrical energy is transferred from batteries
and other sources to other components. Use of
standard electrical symbols in circuit diagrams for
components in series and in parallel. Advantages
and disadvantages of light bulbs wired in series and in
parallel. [Note:
You may be expected to draw circuit diagrams involving
recall of the following symbols; open/closed switch,
cell(s), ammeter, voltmeter, lamp, resistor, variable
resistor and diode] § Heating
effect Yr
10 The
heating effect of a current in a resistor is due to the the
flow of electrical charge through it. Use of the
heating effect in circuits, limited to (i)
hair-dryers (ii)
immersion heaters (iii)
light bulbs § Electrical
resistance Yr
10 1. The
change in the current in an electrical
circuit
is the result of a change in resistance
and/or voltage within the circuit. 2. The
unit of resistance (R) is the ohm
(½) 3. Recall
and use of the definition
of resistance:
R = V/I Circuits Yr
10 1. Series
circuit: total
resistance of resistors in series is equal to sum of all
resistors in circuit. Total p.d. across circuit is sum of
p.d.'s across individual resistors. 2. Parallel
circuit: p.d.
across resistors in parallel is the same for all resistors,
total current through circuit is sum of currents through
individual components. § Current
characteristics Yr
10 Results
and experimental details of investigations into the
variation of current with voltage in the following
devices. (i)
resistors (ii)
wires
made of different metals (iii)
filament
lamps (iv)
diodes For the
higher tier you will also have to know about the variation
of current in (i)
thermistors. (ii)
light
dependent resistors
(LDRs) Electrical
Power Yr
10 Electrical
power
is the rate of transfer of electrical energy
(J/s) Recall and
use of the quantitative relationship: The unit
of electrical power is the watt. § Paying
for electricity Yr
10 1. Domestic supply in U.K
is a.c. at 50Hz and 230 V 2. Calculation of the cost
of using electrical energy using the quantitative
relationships: cost of electricity
supplied (p) = energy transferred (kW h) x price per unit
(pence/kW h) 3. The kilowatt-hour
(kWh) is a unit of electrical energy transferred. § Fuses Yr
10 1. The function of a
fuse
in domestic circuits. 2. Selecting the
appropriate fuse for a given appliance using V = IR and P =
VI 3. Action of
circuit
breakers
(resetable fuses) in domestic electrical
circuits. § Plugs Yr
10 1. Functions of
live,
neutral
and earth
wires in plugs 2. Position of live,
neutral and earth terminals in plug. 3. Colours of insulation
sheathing for live, neutral and earth wires. 4. Role of the fuse in
plugs. § Insulation
and earthing Yr
10 Protection
to users of
electrical equipment, limited to (i) insulation in wiring
and electrical appliances (ii) double
insulation (iii) earthing
of electrical appliances (iv) fuses (v) residual current
circuit
breakers §
GCSE
syllabus: force & motion
GCSE syllabus: electromagnetism
Date Last
Modified: April
2003
Emanuel School, London SW11 !HS
All text and diagrams copyright of J.C.Naylor