Your Hospital

What are sensing circuits ? How do you think sensing circuits

can be used in hospitals?

Key words : Thermistor, Resistance,

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.

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

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.

Calibrating the thermistor

Equipment • Connecting wires • Thermometer• Thermistor• 250 cm3 beaker• Warm water, Ice digital muiltimeter switched

to the ohms range (Ω)

Safety

• Lab Coats• Goggles• Glass aware• Hot water• Equipment

Method

1. Set up the equipment as shown on work sheet

2. Pour hot water into the beaker 3. take the reading of the thermometer and the

Resistance meter4. Change the temperature by adding ice 5. Plot in a graph

Thermistor

• What Circuit detects the change of temperature?

• How does it detect the temperature?

• How does it work?