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powers the connected components (LED and buzzer). Water Conductivity and Circuit Completion:
Water conducts electricity, so when the water touches the sensor, it completes the circuit, allowing
the current to flow. This is how the water level triggers the response from the transistor, which
activates the other components in the circuit.

Observation

Students will observe that when the water level reaches a specific point, the circuit is completed
through the water, activating the NPN transistor. This, in turn, powers the LED to light up and
the buzzer to sound, indicating that the water level has been reached.

They will see how the transistor acts as a switch, controlled by the water level, and understand
how simple circuits can be used to create warning systems or indicators in real-world applications
such as water tanks or flood alarms.

Application

Home Water Tanks: Monitoring and alerting when water
levels are too high or low to prevent overflow or dry runs.

Troubleshooting Tips

1. Ensure all connections are secure and properly inserted
into the breadboard.

2. Verify that the battery is charged and providing adequate voltage.

3. Check the orientation of the transistor, LED, and other components.
4. Make sure the resistor values are correct and properly placed in the circuit.

exercise

A. Tick ( ) the correct option.
1. What is the longer lead of an LED called?

(i) Cathode (ii) Anode

(iii) Resistor (iv) Voltage Regulator

2. What is the purpose of a resistor in a circuit?
(i) To increase the current (ii) To decrease the voltage

(iii) To limit the flow of current (iv) To store energy

3. What happens when a switch in a circuit is turned ON?
(i) It opens the circuit (ii) It closes the circuit

(iii) It increases the resistance (iv) It turns off the power

48 RoboGenius (V1.0)-VIII