3.2.4 Making an Electric Lamp Glow Using an Electric Cell or Battery

Last updated at April 25, 2026 by

What is Making Lamp Glow?

It is the process of connecting electric cell to lamp to produce light .

Key Facts and Examples
  • Lamp glows only when circuit is complete .
Example: Torch working, table lamp switched on, LED indicator glowing
  • One terminal connects to positive and other to negative of cell .
Example: Torch bulb connections, LED connections, circuit connections
  • LED glows only when positive wire connects to longer wire .
Example: LED torch, LED bulb, LED indicator working correctly
  • LED works only in one direction .
Example: LED lights up in correct connection, stays off in reverse
Making Lamp Glow Process Connect wires One to positive, one to negative Complete circuit Current flows through lamp Lamp glows Light is produced Circuit works!

Activity 3.6: Testing Lamp Connections (Page 32)

What you need:

  • Electric cell
  • Incandescent lamp used in torch
  • Cell holder
  • Lamp holder
  • Four lengths of electric wire

What to do:

  • Step 1: Take an electric cell, an incandescent lamp used in a torch, a cell holder, a lamp holder, and four lengths of electric wire
  • Step 2: Remove about 1 cm plastic covering from both ends of each wire
  • Step 3: Make connections and predict if lamp will glow for each arrangement in Table 3.1
💡 Visual Element Detected: Table 3.1 with different connection arrangements

Predictions and Results:

Connection Type Prediction Result Reason
Both wires to positive terminal Will not glow Does not glow Independent path intact
Both wires to negative terminal Will not glow Does not glow Independent path intact
One to positive, one to negative Will glow Glows Circuit complete
No connections made Will not glow Does not glow No circuit

Observations

What you see:

  • Lamp glows only when one wire connects to positive and other to negative
  • Lamp does not glow when both wires connect to same terminal
  • Complete circuit is needed for lamp to work

Why this happens:
We have studied that electric current needs complete path to flow . This is why proper connections are essential .

  • Current flows from positive to negative terminal
  • Incomplete circuit stops current flow
Circuit Connection Results Complete Circuit Incomplete Circuit One to positive Both to same terminal One to negative No current path Lamp glows Lamp does not glow

Activity 3.7: Testing LED Connections (Page 32)

What you need:

  • Two electric cells
  • LED of any colour
  • Cell holder for two cells
  • Two lengths of electric wire

What to do:

  • Step 1: Take two electric cells, an LED of any colour, a cell holder for two cells, and two lengths of electric wire
  • Step 2: Connect battery positive wire to longer wire of LED
  • Step 3: Connect battery negative wire to shorter wire of LED
  • Step 4: Observe if LED glows
  • Step 5: Then interchange wires and observe

Observations

What you see:

  • LED glows when positive wire connects to longer wire
  • LED does not glow when wires are interchanged
  • LED is direction sensitive

Why this happens:
We have studied that LED has positive and negative terminals . This is why correct connection is essential .

  • LED allows current to flow in one direction only
  • Wrong connection blocks current flow
LED Connection Results Feature Correct Connection Wrong Connection Positive wire To longer LED wire To shorter LED wire Negative wire To shorter LED wire To longer LED wire Current flow Flows through LED Blocked by LED Result LED glows LED does not glow
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