Resistors Flashcards
What are ohmic conductors?
Resistors that have a fixed value that does not depend on the current flowing through the circuit
What is Ohm’s Law?
Ohm’s states that the current through the ohmic conductor (at a constant temperature) is directly proportional to the potential difference across the resistor
What graphs do ohmic conductors produce?
Ohmic conductors will produce a straight line I-V graph that goes through the origin
What are non-ohmic conductors?
The resistance of components such as lamps, diodes, thermistors and LDRs is not constant. It changes with the current through the components
Describe the current in a filament lamp
As the current increases, the temperature of the filament increases therefore the resistance of the filament lamp increases
What are diodes?
Diodes are electrical components that only allow a current to flow in one direction only
Describe the resistance in diodes
Diodes have a low resistance in the forward direction but a high resistance in the reverse direction
What are thermistors?
Thermistors are types of resistors where the resistance varies with the temperature
What happens to the resistance of a thermistor when the temperature increases?
The resistance decreases
What are thermistors used for?
Thermistors are used in thermostats to control temperature in homes
What are light dependent resistors (LDRs)?
They are types of resistors where the resistance varies with light intensity
What happens to the resistance of an LDR as the light intensity increases?
The resistance decreases
What are LDRs used for?
LDRs are used as switches to turn on street lights when it gets dark
What do you need to measure the resistance?
The current using an ammeter and the potential difference using a voltmeter
What is the formula to find resistance? (Include units)
R = V x I
Resistance = Potential Difference x Current
Ohms = Volts x Amps
