Question 11 — Using an LED that requires - Questions at the end of the chapter - Chapter 3 Class 7 - Electricity: Circuits and their Components

Q11 (Difficult): Using an LED that requires two cells in series to glow, Tanya made the circuit as shown in Fig. 3.21. Will the lamp glow? If not, draw the wires for correct connections.

Answer:
We have studied that an LED works in one direction only — its longer wire (positive) must connect to the positive terminal of the battery. If connected the wrong way, the LED will NOT glow even in a working circuit.

• Reason 1: LED is connected in the wrong direction
• Reason 2: Battery is discharged or wrongly connected
• Reason 3: Loose or broken wire connection
• Reason 4: LED itself is damaged or fused

How to fix:

• Step 1: Reverse the LED — connect its longer wire (+) to the positive terminal of the battery
• Step 2: Check all wire connections for loose ends
• Step 3: Replace battery with a fresh one to rule out dead battery
• Step 4: Test with a different LED to check if original is damaged

Key Point: An LED is direction-sensitive (unlike a bulb). Always connect the LED's longer wire (+) to the battery's positive terminal.