1. Your Hospital What are sensing circuits ?
Key words : Thermistor, Resistance,
What are sensing circuits ?
How do you think sensing circuits can be used in hospitals?

2. Lesson outcomes By the end of this lesson I will be able to:
describe how a thermistor detects changes in temperature
describe how sensors can be used in hospitals.

3. What is a Thermistor?
A thermistor is a temperature-dependent resistor.
It monitors the temperature and can be used like a switch to control the temperture
Used in fire alarms and incubators in hospital

4. How does it work?
At low temperatures, the resistance of a thermistor is high, and little current can flow through them.
At high temperatures, the resistance of a thermistor is low, and more current can flow through them.

5. Calibrating the thermistor
Equipment
Connecting wires
Thermometer
Thermistor
250 cm3 beaker
Warm water, Ice digital muiltimeter switched to the ohms range (Ω)
The ohm is defined as a resistance between two points of a conductor when a constant potential difference of 1.0 volt, applied to these points, produces in the conductor a current of 1.0 ampere, the conductor not being the seat of any electromotive force.

6. Safety
Lab Coats
Goggles
Glass aware
Hot water
Equipment

7. Method Set up the equipment as shown on work sheet
Pour hot water into the beaker
take the reading of the thermometer and the Resistance meter
Change the temperature by adding ice
Plot in a graph

8. Thermistor What Circuit detects the change of temperature?
How does it detect the temperature?
How does it work?