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killthemoment
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GCSE Physics (P2) Mind Map on P2.3 Currents In Electrical Circuits, created by killthemoment on 10/08/2014.
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2017-03-19T17:33:50Z
P2.3 Currents In Electrical Circuits
P2.3.1 Static
Electricity
P2.3.2 Electrical
Circuits
When certain insulating materials are
rubbed against each other they become
electrically charged. Negatively charged
electrons are rubbed off one material and
onto the other.
The material that gains electrons
becomes negatively charged. The
material that loses electrons is left with
an equal positive charge.
When two electrically charged objects are brought together they exert a force on
each other.
Two objects that carry the same
type of charge repel. Two objects
that carry different types of
charge attract.
Electrical charges can move
easily through some
substances, for example
metals.
Electric current is a flow of electric
charge. The size of the electric
current is the rate of flow of electric
charge. The size of the current is
given by the equation: I=Q/t where I
is the current in amperes (amps), A,
Q is the charge in coulombs, C and t
is the time in seconds, s.
The potential difference (voltage)
between two points in an electric
circuit is the work done (energy
transferred) per coulomb of charge
that passes between the points.
V=W/Q where V is the potential
difference in volts, V, W is the work
done in joules, J and Q is the charge in
coulombs, C.
Currentāpotential difference graphs are used to show how the
current through a component varies with the potential
difference across it.
The resistance of a component can be
found by measuring the current through,
and potential difference across, the
component. The current through a
resistor (at a constant temperature) is
directly proportional to the potential
difference across the resistor.
V=IĆR where V is the potential
difference in volts, V, I is the current in
amperes (amps), A and R is the
resistance in ohms, Ī©.
The current through a component
depends on its resistance. The greater
the resistance the smaller the current
for a given potential difference across
the component.
The potential difference provided by
cells connected in series is the sum of
the potential difference of each cell
(depending on the direction in which
they are connected).
For components connected in
series the total resistance is the
sum of the resistance of each
component, there is the same
current through each component
and the total potential
difference of the supply is shared
between the components.
For components connected in parallel the
potential difference across each component is
the same and the total current through the
whole circuit is the sum of the currents through
the separate components.
The resistance of a
filament bulb increases
as the temperature of
the filament increases.
The current through a diode flows in one direction only. The
diode has a very high resistance in the reverse direction.
An LED emits light when a current
flows through it in the forward
direction.
The resistance of a light-dependent
resistor (LDR) decreases as light
intensity increases. The resistance of
a thermistor decreases as the
temperature increases.
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1134180
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2017-03-19T17:33:50Z
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