Aim:

To study the behavior of bulbs connected in series and observe changes in brightness.

Apparatus Required:

• Bulbs (same wattage) – 2 or more

• Lamp Holders

• Connecting Wires

• One way Switch

• Fuse

• Power Supply (AC 230V)

• Voltmeter

• Ammeter

• Screwdriver, Wire Stripper

Procedure:

1. Turn Off Power Supply – Ensure the power source is switched off before making connections.

2. Fix the Lamp Holders – Mount the lamp holders on the wiring board.

3. Connect Bulbs in Series:

   • Take two or more bulbs and connect them end-to-end (one bulb’s output terminal to the next bulb’s input terminal).

   • Use insulated copper wires for connections.

4. Connect to Power Source:

   • Attach one end of the series connection to the live terminal of the power supply.

   • Connect the other end to the neutral terminal through a switch and a fuse.

5. Insert Ammeter in Series – Place an ammeter in series to measure current flow.

6. Insert Voltmeter Across Each Bulb – Place a voltmeter across individual bulbs to measure voltage drop.

7. Switch ON the Circuit – Turn on the power supply and observe the bulbs.

8. Switch OFF the Circuit – Ensure safety by switching off the power before making modifications.

Observations:

• Bulbs in series receive equal current, but voltage divides among them.

• If one bulb fails, the entire circuit is broken.

• Bulbs glow dimmer compared to parallel connections due to voltage drop.

Precautions:

1. Ensure all connections are tight and secure to prevent loose contacts and sparking.

2. Use properly insulated wires to avoid short circuits and electric shocks.

3. Always switch off the power supply before making any wiring changes.

4. Use a fuse of appropriate rating to protect the circuit from overcurrent.

5. Avoid touching live wires while the circuit is powered on.

6. Verify voltage readings carefully using a properly calibrated voltmeter.

7. Ensure the bulbs are properly rated for the supply voltage to prevent damage.

8. Follow all safety protocols and use necessary protective equipment while working with electrical circuits.

Result:

The experiment demonstrates that in a series circuit, the same current flows through all components, but the voltage divides among them. The brightness of bulbs is reduced compared to a parallel circuit.

Circuit Diagram: