Red Seal Electrician Practice
Signalling and communicationQuestion 47 of 1506

Which parts make up a typical optical fibre cable, from the inside out?

  1. Copper core, paper insulation, steel armour and a lead sheath over it
  2. Glass core and cladding, plastic coating, kevlar fibres, and an outer sheath
  3. Glass core, copper shield, rubber filler and a metal braid on the outside
  4. Plastic core, glass cladding, copper wire and a foil wrap under the outer jacket
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Correct answer: Glass core and cladding, plastic coating, kevlar fibres, and an outer sheath

Kevlar gives tensile strength. The thin glass is flexible.

Source: Lessons in Electric Circuits IV: Digital (Kuphaldt), 14.5: Optical Data Communication

Practice signalling and communication

Questions last reviewed: 18 October 2026