Fire Alarm Investigation

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Jahedur Rahman        10S        Fire Alarm Investigation

                                Fire Alarm Investigation


In this investigation I will be making a fire alarm for an old person’s home. I will make a model then test it to see if it is suitable for an elderly home.

This investigation is mainly on finding a resistor which will turn on only in the case of a fire by a switch which will detect the fire early thus causing an evacuation of the home.


In my investigation I plan to use an electromagnetic bell which will ring only when the switch is activated by fire. My switch will be a negative thermal coefficient thermistor which has high resistance when the temperature is cold but low resistance when the temperature is hot, which will cause it to activate the electromagnet as this will complete the circuit. When the magnet is turned on it will pull on a disc of metal towards it connected to this disc is a hammer. When the magnet is turned on the hammer will be attracted and it will hit the bell. When it hits the bell the circuit will be broken so the hammer will return to its original position consequently restarting the process yet again.



Power Supply x1                                                NTC Thermistor

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                                                        (Negative Thermal Co efficient)

Wire                                                        Iron Core for Electromagnet

Hammer x1                                                Bell x1

Metal Disc (magnetic) x1                                Bunsen burner x1

Cup of Water with ice                                        Heatproof mat

Risk Assessment

There are a lot of safety issues in this investigation. There is the risk of electrocution from the wires as at the end it is only live wire and if not use properly it may be fatal.

The power supply ...

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