Resistance & V= I X R Flashcards
What does the filament lamp graph show in terms of resistance?
As the temperature of the filament increases the resistance increases creating a curve
In a diode , where does current flow?
Current will only flow through a diode in one direction. The diode has very high resistance in the opposite direction
What is the equation involving potential difference, current and resistance?
P.D = current X resistance
V = I X R
What is a diode?
A diode is a special device made from semiconductor material such as silicon.
What is a diode used for?
It is used to regulate the potential difference in circuits
What does a light emitting diode do ?
A light emitting diode (LED)emits a light when a current flows through it in the forward direction
Why are LEDs commonly used in lighting?
They use a much smaller current than other forms of lighting
What is a light dependent resistor “LDR” ?
And LDR is a resistor that is dependent on the intensity of light
How does the LDR work?
In bright light the resistance falls.
In darkness the resistance is highest.
What is a thermistor?
A thermistor is a temperature dependent resistor
How does a thermistor work?
In hot conditions the resistance drops.
In cool conditions the resistance goes up.
What are thermistors useful to make?
Temperature detectors such as a car engine temperature sensor
What are the units of resistance?
Ohms
Write down the formula that links potential difference, work done and charge
P.d = work done \ charge
Give one use of a light dependent resistor LDR…
Automatic night lights
Outdoor lighting
Burglar detectors
