There are 4 detection devices: door switch, window foil, pressure mat, passive intra-red detector.. The bell would rang if the door is opened, if glass is broken, if there is movement in
Trang 1Alarm system Task 2:
1 Alarm system
2 There are 4 detection devices: door switch, window foil, pressure mat, passive intra-red detector
3 Bell
4 Because they want nobody can control this system except the host
5 The bell would rang if the door is opened, if glass is broken, if there is movement in the room
6 The problem is about control box If the bad guys destroyed the control box, every devices would be counteracted
Task 3:
1 Door switch:
The use magnetic switches on door A magnet mounted on the morning part of the door trips a switch mounted on the frame when the door is opened
2 Window foil:
They fit Break detectors on the inside surface of glass in windows If the glass is broken the foil breaks too
3 Pressure mats:
The fit them under the carpet at the bottom of the stairs/ the pressure of someone stopping on them causes two thin metal plates inside to come in contact, setting off the alarm
4 Passive intra-red detector:
They use passive intra-red to detect movement within their range
Task 4:
Task 5:
1 C The alarm continues to operate on batteries if a burglar disconnects the supply
2 E If the glass is broken, the foil breaks too
3 F If a door is opened, a magnet on the door trips a switch on the frame
4 A If a window is opened, a magnet on the moving part trips a switch
5 G If you’re not there to reset the system, the alarm stops after a set time
6 B Tamper sensors trigger the alarm if a burglar tries to force the alarm open
7 D If someone steps on them, two thin metal plates come in contact
Task 6:
1 Two thin metal plates come in contact
2 You won’t bet off the alarm when leaving
3 The noise goes on the for hours
Trang 24 The motion sensor detect movement within their range
5 The glass is broken
6 The burglar tries to force the alarm open
7 The doors or windows are opened
8 You fit are automatic cut-off
Task 8:
1 F
2
Task 9:
1
Thermistor Heat Microphone Sound 2 Switch off and by the electronic switch
3 The increased current causes the relay to operate and switch on the output circuit
4
Fixed resistor Rheostat Increases Diminished Energize
To cause Forward bias
Task 10:
1 The diagram shows a reed switch
2 Because the reeds are sealed in a glass envelope to the protect them
3 Because it helps to prevent corrosion of the contacts
4 When a magnet is bought close to the reeds, they are magnetized, attract each other, and close When the magnet is removed, the reeds open