Purity of electrical grade aluminium should be ≥ _____________ percent?

Related Mcqs:

1. Straight silicon steel (containing Si from 0.5 to 5%) because of their low hysteresis loss and high magnetic permeability are used for electrical appliances. Which of the following electrical appliances made of silicon steel contains maximum percentage of silicon (about 4%) ?

   A. Armature of small motors/generators
   B. Generators and small motors
   C. Induction motors
   D. High frequency transformers

2. Alinco, which is a aluminium-cobalt-nickel steel, is used for making __________________?

   A. Surgical instruments
   B. Powerful magnets
   C. Chemical equipments
   D. Boiler tubes

3. Aluminium alloy is one of the most suitable materials of construction for aircrafts mainly due to its___________________?

   A. High strength to weight ratio
   B. Low temperature strength properties
   C. Its ability to be cast, rolled, forged & stamped
   D. High strength and corrosion & oxidation-resistance at elevated temperature

4. Aluminium as a material of construction suffers from the disadvantage of__________________?

   A. Very high cost
   B. Rather low tensile strength
   C. Very low strength to weight ratio
   D. Scarce availability

5. Aluminium storage vessel can be used to store________________?

   A. Aqua regia
   B. Ferrous sulphate
   C. Hydrochloric acid (10%)
   D. None of these

6. The electrical conductivity of a ______________ decreases with rise in temperature?

   A. Metal/alloy
   B. Semi-conductor
   C. Dielectric
   D. None of these

7. Which of the following alloy steels has the energy saving properties making it suitable for use in electrical machines ?

   A. Silicon steel
   B. Chromium steel
   C. Molybdenum steel
   D. None of these

8. Presence of even very minute amount (say 0.1%) of ______________ in copper, reduces its electrical conductivity very seriously?

   A. Bismuth
   B. Arsenic
   C. Antimony
   D. Both B. and C.

9. Steel will respond to hardening by heat treatment processes, only when the minimum carbon content in it is _____________ percent?

   A. 0.02
   B. 0.2
   C. 0.35
   D. 0.5

10. The impure iron (pig iron) that is tapped out from blast furnace contains about _____________ percent carbon?

    A. 0.2
    B. 2
    C. 4
    D. 8