Circuit Devices Flashcards
what factors can resistance depend on in a circuit
temperature and light intensity
what is an LDR
a light dependent resistor that is dependent on the intensity of light
how do LDRs respond to stimuli
- in bright light, the resistance falls
- in darkness, the resistance is highest
what can LDRs be used in
automatic night lights or burglar detectors
what is a thermistor
a temperature dependent resistor that is dependent on the temperature
how do thermistors respond to stimuli
- in hot conditions, the resistance drops
- in cold conditions, t he resistance increases
what can thermistors be used in
temperature detectors, car engine temperature sensors and electric thermostats
what can sensing circuits be used for
turning on/ increasing the power to components depending on the conditions that they are in
if you were to have a fan and a fixed resistor connected in a parallel circuit, how would the potential difference be distributed
the fan and resistor will both have the same potential difference because the electrons still have the same energy, eventhough the current is what is split
in a circuit, the potential difference of the power supply is shared out between the thermistor and the loop made up of a fixed resistor and the fan according to their resistances (the parallel bit). this means that…
the bigger a component’s resistance, the more of the potential difference it takes
in a circuit with a thermistor and fixed resistor in it, the room gets hotter so the resistance of the thermistor decreases, meaning it takes a smaller share of the potential difference from the power supply. how would this affect a fan if it were in the circuit
the potential difference across the fixed resistor and the fan rises, which gives the fan more energy meaning it can go faster
if you connect a bulb in parallel to an LDR, what would be potential difference and resistance be across the components when its dark
the potential difference would be high when its dark and the LDR’s resistance would be high
the greater the potential difference across a component…
the more energy it gets
