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Activity Industry Sector
Transportation

Activity Originally Created By: MaryRose Lovgren

Importance of Relays

Part of Lesson Plan: Operation and Testing of Relays (updated) by Mike Monahan

Activity Overview / Details

Do this demonstration using actual headlights on high beams.

- Using a test board, show a long wire approximately 15 foot long that runs the head lights.

- Then, show a relay in the circuit .  More current to the head lights= brighter lights

- To make this more dramatic, use a longer wire or put on more lights.

- Less voltage drop = more current going where needed.

Materials / Resource

  • headlight diagram headlight diagram [ Download ] This diagram without relay and long wire - showing voltage drop (duller lights)
  • headlight-relays.gif headlight-relays.gif [ View Image ] [ Download Original ] A drawing of a head light relay