Stretch the Chain and See the Light

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In this activity, learners use their strength to light a light bulb. A chain made from paper clips is placed in series with a battery and flashlight bulb. When the chain is stretched, the light bulb glows brighter. The explanation lies in decreased electrical resistance due to better contact between the paper clips as the chain is stretched.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
10 to 30 minutes

Estimated Materials Cost:
$5 - $10 per group of students

Age Range:
Ages 11 - 18

Resource Types:
Activity, Demonstration


Materials List (per group of students)

  • Christmas tree bulb cut from a string of lights
  • approximately 3 ft of hook up wire (#22 solid copper wire) or alligator clip leads
  • battery - AA
  • 2 paper clips - regular size (#1)
  • 2 finishing nails - 2 1/2 inches long
  • wirestripper
  • tape
  • 18-24 inches of steel chain


  • Engineering and Technology
    • Engineering
      • Electrical Engineering
  • Physical Sciences
    • Electricity and Magnetism
      • Electric Charges and Currents
      • Electric Circuits
  • The Nature of Science
    • The Scientific Process
      • Conducting Investigations

Informal Categories

  • Electronics


To use this activity, learners need to:

  • see
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access


  • Rathjen, Don


  • All rights reserved, Exploratorium, 2004