12.4 Components And Their Characterisitcs Flashcards
what is a battery
a combination of cells
what is the symbol of a light source e.g lamp known as
an indicator
what does a diode do
only allows the current in one direction
What does a light-emitting diode do
emits light when it conducts
the direction in which the diode conducts is referred to as its forward direction
the opposite direction is referred to as its reverse direction
examples of when diodes are used
the protection of dc circuits in case the voltage supply is connected the wrong way round
what is a resistor
a component designed to have a certain resistance
what happens to the resistance of a thermistor
decreases with increasing temperature
as it is an intrinsic semiconductor and is often things such as silicon
when does the resistance of a light dependent resistor LDR decrease
with increasing light intensity
what can you use to measure the variation of current with PD for a component
a potential divider to vary the PD from 0
or
a variable resistor to vary the current to a minimum\
what is the advantage of using a potential divider
the current through the component and the pd across it can be reduced to 0
this isn’t possible for a variable resistor circuit
what goes on each axis
current on the y axis
potential difference on the x axis
what is used to measure wire, lamp and thermistor graphs
An ammeter sensor and a voltmeter sensor connected to a data logger could be used to capture the data and can be displayed directly on an oscilloscope or a computer
wire graph
A wire gives a straight line through the origin
This means that on any point on the line, the value of v/I doesn’t change
Therefore in other words, meaning that the resistance of the wire doesn’t change when the current changes
what is the gradient of a wire graph equal to
1/ resistance
what would any resistor at constant temperature give
a straight-line
filament bulb graph
gives a curve with a decreasing gradient because the resistance increases as it becomes hotter
thermistor graph
gives a straight line at a constant temperature
The higher the temperature, the greater the gradient of the line because the resistance falls with increase of temperature
the same result is obtained for lDR in respect to light intensity
