Brief P2 Flashcards
How draw Circuit symbol fr..
-I i-
+ -
How draw lamp
Circle with x fr
How draw fuse
Rectangle with line thru
How draw diode
Play button
How draw resistor
Rectangle
How draw thermistor
Ugly tick starting from bottom left
How draw variable resistor
Actual tik
Draw LDR
two ticks coming into a circle with a rectangle inside
Draw LED
tick bouncing off
Diode symbol
What is an ohmic conductor and state the conditions required
A Conductor for which current and potential difference are directly proportional
Resistance remains constant as current changes
Temperature must be constant
4 components for which resistance is not constant as current changes
Lamps
Diodes
Thermistors
LDR
What happens to resistance of a filament lamp as the temperature increases and why
(4 marks)
Resistance increases
Ions in metal have more energy so collide more frequently with electrons as they flow through the metal - creating greater resistance to current flow
What is different about current flow through a diode
Current flow in one direction
Resistance is very high in the other direction preventing current flow
What is different about current flow through a diode
Current flow in one direction
Resistance is very high in the other direction preventing current flow
Two examples of when a thermistor may be used
In a thermostat to turn a heater on below a certain temperature
In a freezer to turn on a cooler when the temperature becomes too high