6.2.1 Current, potential difference and resistance Flashcards
For electrical charge to flow through a closed circuit, what must the circuit include?
a source of potential difference
what is electrical current?
Electric current is a flow of electrical charge. The size of the electric
current is the rate of flow of electrical charge.
charge flow, Q is measured in
coulombs, C
current, I is measured in
amperes, A
current in a single closed loop.
A current has the same value at any point in a single closed loop.
what does the current (I) through a component depend on?
The current (I) through a component depends on both the resistance (R) of the component and the potential difference (V) across the component
The greater the resistance of the component?
the smaller the current for a given potential difference (pd) across
the component.
potential difference and voltage are?
the same thing
for some resistors, the
value of R remains constant. Why is this not for all resistors?
in others, resistance can change as the
current changes.
The current through an ohmic conductor (at a constant temperature) is?
directly proportional to the potential difference across the resistor. This means that the resistance remains constant as the current changes.
For some components the resistance is not constant; it changes with the current through the component. Give examples of these.
lamps, diodes, thermistors
and LDRs
The resistance of a filament lamp
The resistance of a filament lamp increases as the temperature of
the filament increases
The current through a diode?
flows in one direction only
the resistance of a dioide
The diode has a very high resistance in the reverse direction.
the resistance of a thermistor
The resistance of a thermistor decreases as the temperature increases
