Sensing Circuits

Question 1

What can sensing circuits be used for?

Answer 1

Sensing circuits can be used to turn on or increase the power to components depending on the conditions that they are in.

Question 2

Thermistor in a sensing circuit with a fan

Answer 2

1) The fixed resistor and the fan will always have the same potential difference across them because they’re connected in parallel.
2) The potential difference of the power supply is shared out between the thermistor and the loop made up of the fixed resistor and the fan according to their resistances-the bigger a component’s resistance, the more of the potential difference it takes.
3) As the room gets hotter, the resistance of the thermistor decreases and it takes a smaller share of the potential difference from the power supply. So the potential difference across the fixed resistor and the fan rises, making the fan go faster.

Question 3

Sensing circuit with an LDR and a variable resistor

Answer 3

1)You can connect the component across the variable resistor instead of across the fixed resistor
2) For example, if you connect a bulb in parallel to a LDR, the [