3.2.5 An Electrical Circuit

Last updated at April 25, 2026 by

What is Electrical Circuit?

It is a complete path that allows electric current to flow from positive to negative terminal .

Key Facts and Examples
  • Simple electrical circuit consists of electric cell , connecting wires , switch , and electric lamp .
Example: Torch circuit, table lamp circuit, LED circuit
  • Switch is a simple device that completes or breaks a circuit .
Example: Light switch, torch switch, fan switch
  • Direction of electric current is from positive to negative terminal .
Example: Current flow in torch, current flow in LED circuit
  • Closed circuit allows current to flow and lamp glows .
Example: Torch switched on, room light on, LED indicator glowing
  • Open circuit stops current flow and lamp does not glow .
Example: Torch switched off, room light off, broken wire
Open vs Closed Circuit Property Closed Circuit Open Circuit Switch position ON - connected OFF - gap present Current flow Current flows No current flow Lamp condition Lamp glows Lamp does not glow Circuit path Complete path Broken path

Question (Page 32): How does a switch turn on or off the torchlight?

Answer:
We have studied that switch completes or breaks the circuit . This is why it controls the torch .

  • Switch ON completes circuit and allows current flow
  • Switch OFF breaks circuit and stops current flow
How Switch Controls Torch Switch ON Completes circuit path Current flows From positive to negative Lamp glows Torch produces light Torch works!

Activity 3.8: Making a Simple Switch (Page 32)

What you need:

  • Two drawing pins
  • Safety pin (or paper clip)
  • Two wires
  • Small piece of cardboard

What to do:

  • Step 1: Collect two drawing pins, a safety pin (or a paper clip), two wires, and a small piece of cardboard
  • Step 2: Insert a drawing pin through the ring of the safety pin
  • Step 3: Make a switch

Observations

What you see:

  • Safety pin can rotate around drawing pin
  • Switch has two positions - touching and not touching
  • Simple materials can make a working switch

Why this happens:
We have studied that switch needs to complete or break circuit . This is why simple design works.

  • Metal parts conduct electricity when touching
  • Air gap stops current flow when not touching
Homemade Switch Positions Switch ON Switch OFF Safety pin touches pin Safety pin away from pin Metal contact made Air gap present Current can flow No current flow

Activity 3.9: Testing Circuit with Switch (Page 32)

What you need:

  • Electric cell
  • Lamp
  • Switch (made in Activity 3.8)

What to do:

  • Step 1: Connect the electric cell, lamp, and switch
  • Step 2: Observe if lamp glows
  • Step 3: Rotate the free end of the safety pin till it touches the second drawing pin
  • Step 4: Observe if lamp glows now

Question (Page 32): Does the lamp glow?

Answer:
We have studied that lamp needs complete circuit to glow . This is why switch position matters.

  • Switch OFF creates air gap and lamp does not glow
  • Switch ON completes circuit and lamp glows

Question (Page 32): Now does the lamp glow?

Answer:
We have studied that closed circuit allows current flow . This is why lamp glows when switch is ON .

  • Safety pin touches drawing pin and completes circuit
  • Current flows through complete path and lamp glows
Complete Circuit Operation Switch closed Safety pin touches drawing pin Circuit complete Current flows through all parts Lamp glows Light is produced Circuit works perfectly!

Observations

What you see:

  • Lamp does not glow when switch is OFF
  • Lamp glows when switch is ON
  • Switch controls the circuit effectively

Why this happens:
We have studied that electric current needs complete path . This is why switch controls lamp .

  • Open switch breaks circuit and stops current
  • Closed switch completes circuit and allows current

Section Summary: A Simple Electrical Circuit

A Simple Electrical Circuit Summary Electric Cell Portable energy source with terminals Battery Two or more cells connected Electric Lamp Incandescent bulb or LED Making Lamp Glow Complete circuit needed Electrical Circuit Complete path with switch
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