Logic Gates

A streetlight automatically turns ON when it is dark and a person is detected nearby.

• Dark → represented by logic 1

• Person detected → represented by logic 1

Which logic gate best represents this requirement?

• AND

• OR

• NOT

• NAND

Fire Alarm System

A fire alarm rings if smoke is detected OR the temperature is above 60°C.

• Smoke sensor → 1 when smoke is present

• Temperature sensor → 1 when above 60°C

Which gate will trigger the alarm correctly?

• NOR

• OR

• AND

• NAND

Burglar Detection

A burglar alarm should remain silent only when BOTH the main door and the window are closed.

• Door closed → 1

• Window closed → 1

If either is open, alarm should sound. Which gate produces this logic?

• NAND

• NOR

• AND

• XOR

Industrial Machine Safety

A machine stops if emergency stop button is pressed OR safety door is open.

• Emergency stop pressed → 1

• Safety door open → 1

Which gate output should be used to stop the machine?

• AND

• OR

• XOR

• NAND

Car Seatbelt Warning

The seatbelt warning light turns ON if the ignition is ON and seatbelt is NOT fastened.

• Ignition ON → 1

• Seatbelt fastened → 1

Which logic?

• AND with NOT on seatbelt input
  

• OR with NOT on seatbelt input
  

• 
  NAND with NOT on ignition input
  

• XOR