Answer: Logic Lights #147

The lamp is OFF. It stays dark!

The solved circuit. Wires carrying power glow yellow. The lamp is off.
Yellow wires carry power. Grey wires don’t.

Gate by gate

  1. NOT B → NOT ON = OFF
  2. A AND NOT B → ON AND OFF = OFF
  3. C AND D → OFF AND ON = OFF
  4. (A AND NOT B) AND (C AND D) → OFF AND OFF = OFF

The same circuit in Python

Python has the same three gates built in: and, or and not. ON is True and OFF is False.

A = True
B = True
C = False
D = True

lamp = (A and not B) and (C and D)
print("Is the lamp on?", lamp)

When you run it, it prints:

Is the lamp on? False

Try it: change one of the switches from True to False (or the other way round) and run the code again. Can you find a switch that changes the lamp?