IOCL Junior Operator MCQ Part-8 || IOCL Junior Operator General Science Questions and Answers11. What materials are used for armouring?1 . Galvanized steel wire or steel tape 2 . Rubber or plastic. 3 . Paper or cloth. 4 . Wood or glass Answer and SolutionAnswer: "Galvanized steel wire or steel tape "Galvanized steel wire or steel tape is used for armouring. Discuss12. Why should cable insulation be non-hygroscopic?1 . To increase conductivity 2 . To add flexibility 3 . To increase mechanical strength 4 . To prevent moisture absorption Answer and SolutionAnswer: "To prevent moisture absorption " Cable insulation is non-hygroscopic because it prevent moisture absorption. Moisture reduces insulation resistance and can cause breakdowns. Discuss13. Why is a lead sheath used for hygroscopic insulation?1 . To increase conductivity 2 . To provide a waterproof covering 3 . To add color 4 . To make the cable lighter Answer and SolutionAnswer: "To provide a waterproof covering "The lead sheath prevents moisture from reaching the insulation. Discuss14. What should insulating material be unaffected by?1 . Light 2 . Acids and alkalies 3 . Heat 4 . Cold Answer and SolutionAnswer: "Acids and alkalies "Insulating material should unaffected by acids and alkalies to avoid any chemical action. Discuss15. What is a major drawback of pure rubber as an insulating material?1 . High dielectric strength 2 . Readily absorbs moisture 3 . High temperature resistance 4 . Excellent mechanical strength Answer and SolutionAnswer: "Readily absorbs moisture "Pure rubber absorbs moisture which significantly reduces its insulating properties. and has a low maximum safe temperature. Discuss16. What is the maximum safe temperature for pure rubber insulation?1 . 100°C 2 . 200°C 3 . 38°C 4 . 500°C Answer and SolutionAnswer: "38°C " The maximum safe temperature for pure rubber insulation is 38°C. Pure rubber degrades at relatively low temperatures. Discuss17. What is the range of relative permittivity for rubber?1 . 1 to 1.5 2 . 2 to 3 3 . 5 to 6 4 . 10 to 12 Answer and SolutionAnswer: "2 to 3 " Relative permittivity, also known as dielectric constant, indicates how much a material can store electrical energy in an electric field. The range of relative permittivity for rubber is 2 to 3. Rubber’s value in this range signifies moderate energy storage capability. Discuss18. What is the approximate dielectric strength of rubber?1 . 30 KV/mm 2 . 0 KV/mm 3 . 20 KV/mm 4 . 50 KV/mm Answer and SolutionAnswer: "30 KV/mm "Dielectric strength is the maximum electric field a material can withstand before breakdown. 30 KV/mm means rubber can resist a significant voltage per millimeter of thickness. Discuss19. What is the resistivity of rubber insulation?1 . 1010 Ω cm 2 . 1015 Ω cm 3 . 1017 Ω cm 4 . 1020 Ω cm Answer and SolutionAnswer: "1017 Ω cm " Resistivity measures a material’s opposition to electrical current. A high value like 1017 Ω cm indicates rubber is a good insulator, resisting current flow effectively. Discuss20. What mechanical property makes rubber unsuitable for some applications?1 . Softness and susceptibility to damage 2 . High hardness. 3 . High elasticity 4 . High tensile strength. Answer and SolutionAnswer: "Softness and susceptibility to damage "Rubber’s softness makes it vulnerable to damage from rough handling or mechanical stress, reducing its durability. Discuss123456789
