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P2 - Electricity (End of Y10 Mock) - Coggle Diagram
P2 - Electricity (End of Y10 Mock)
L1 - Circuit Diagrams
Batteries
are
two cells joined together
by their
opposite poles
(with positive on the left and negative on the right)
LDR
(Light Dependant Resistors) are drawn as a
resistor with a ring around it
,
two arrows
(indicating light) are shown to
enter the resistor
L2 - Charge, Current and Time
Charge = Current x Time
Q = I x t
Charge
is measured in
Coulombs
,
current
is measured in
Amps
Current
is the
rate of flow of electric charge
, it
remains the same
at every point in a
closed
,
series
circuit.
Energy Transferred = Charge x Voltage
E = Q x V
L3 & L4 - Ohm's Law
Resistance
(measured in Ohm's) is defined as the the
opposition of current flow
. Resistance is the
result of collisions between metal ions and electrons
within a wire.
Voltage = Current x Resistance
V = I x R
Voltage
is measured in
volts
,
current
is measured in
amps
and
resistance
is measured in
Ohms
.
Voltage
is the
difference in electrical energy between two points.
As the
length of a wire increases
, the
resistance increases
with a
proportional
relationship (given that potential difference is fixed) as there are more metal ions for flowing electrons to collide with.
Ammeters
are always
placed in series
,
voltmeters are always placed in parallel
to the component.
L5 - Resistance in a Filament Bulb
The
Current-Voltage characteristic
of a
filament bulb
is
not linear
, as the
temperature of the filament increases
, metal ions within the filament possess more kinetic energy so it is
harder for electrons to flow
through the wire (resistance increases).
L6 - IV Characteristics
A
fixed resistor
allows for the control over a circuit's current. The current-voltage graph of one of these resistors shows
direct proportion.
A filament bulb
will begin to
increase
in
temperature
as current is passed through it, this henceforth
increases the potential difference
across the component. An
increase in temperature also increases the resistance
of the component.
A
diode
is an electrical component that only
allows for current to pass through it in one direction
(the forward direction). A diode is
not an Ohmic conductor
; its
resistance in the forwards direction is lesser
(effectively zero)
than its resistance in the opposite direction.
L7 - Series and Parallel Circuits
Within a
series circuit
,
current remains the same
throughout but the
voltage is the sum of the voltage of all components
in the circuit. Additionally, in a series circuit,
total resistance will be the sum of the resistance
of all components
within the circuit.
Potential difference is the value of the energy lost across each component.
Within a
parallel circuit,
current is split across branches
because electrons have multiple routes to take; the
current across each component will sum to the total current provided
to the circuit.
Voltage will always be the same within a parallel circuit
, no matter where it is measured from.
L8 - Total Resistance
The
total resistance of a series circuit will increase as the number of resistors increases
; in a
parallel circuit
,
increasing the amount of resistors decreases the resistance.
L9 - Mains Electricity
Alternating current
is a current that
changes direction many times over a period
.
Direct current
is a
current that travels in only one direction
; a battery produces a direct current.
Mains electricity
in the UK has an
alternating current
; alternating at a
frequency of 50 Hz
(50 alternations per second). This mains electricity also has a
voltage of 230 V
The
earth wire
inside of a plug is
stripy
(
can ground the current
if there is a fault in the device). The
live wire is brown
(
carries the alternating, 230V current
) and the
neutral wire is blue
(completes the circuit, 0 V).
L10 - Electrical Power
The amount of
energy
an appliance uses
over time
is
referred to as its power
.
E = P x t
Energy
=
Power
x
Time
Joules
=
Watts
x
Seconds
Power = Current x Voltage
Power = (Current^2) x Resistance
The
national grid
is a
network of transformers and cables
that
transport electricity around the country.
The process
begins with a power station supplying large voltage,
this is then
increased by a step up transformer
; transported across cabling and
delivered to a step down transformer
so that it can be used domestically.
Voltage is increased
during the national grid process
because it ensures that a minimum heat is lost
(
current is reduced
) but
power is not effected.
L11 - Electrical energy
Work is done
when
charge moves around a circuit
(flow of charge = current); therefore
Energy = Charge x Potential Difference
L12 - Static Electricity
When two materials (
electrical insulators
)
rub against one another
,
one
of the materials
will lose electrons
and
one can gain electrons
. The one that has
lost electrons will gain a positive charge
, the one that had
gained electrons will now have an equal, negative charge
.
A charged object creates an electric field
around itself, the
field is stronger closer to the object
. If a second, charged object enters this field; a force will be exerted on it (repulsion or attraction depending on the charge);
this force gets stronger as the objects get closer.
When representing
electric fields
,
arrows indicate
the
direction
at which a
positive charge would move
given the circumstances.
