A. Induction hardened copper
B. Hard drawn copper
C. Pure annealed copper
D. Copper containing traces of silicon
Related Mcqs:
- Due to which of the following reasons copper and aluminium are not used for heating elements ?
A. Both have great tendency for oxidation
B. Both have low melting point
C. Very large length of wires will be required
D. All of the above - Due to which of the following fact, in India, aluminium is replacing copper ?
A. Aluminium is more ductile and malleable than copper
B. Aluminium is available in plenty, cheaper and lighter than copper
C. Aluminium has lower resistivity than that of copper
D. Aluminium has less temperature co-efficient than copper - Copper, even though costly, finds use in the windings of electrical machines because_____________?
A. copper points offer low contact resistance
B. copper can be easily soldered and welded
E. copper windings are less bulky and the machines become compact
D. all of the above - The conductivity of a conductor can be increased by_______________?
A. decreasing its temperature
B. increasing its temperature
C. decreasing its vibration
D. increasing its vibration - Super conductivity can be destroyed by_____________?
A. adding impurities
B. reducing temperatures
C. application of magnetic field
D. any of the above - The conductivity of a metal is determined by____________?
A. the electronic concentration and the mobility of the free electrons
B. the number of valence electrons per atom
C. either (A) or (B)
D. none of the above - The conductivity of an extrinsic semiconductor with temperature________________?
A. decreases
B. increases
C. remains constant - Which of the following is the poorest conductor of electricity ?
A. Carbon
B. Steel
C. Silver
D. Aluminium - Carbon bearings are used under which of the following conditions ?
A. Where lubrication is difficult or im-possible
B. Where corrosive chemical action exists
C. Where high temperature exists
D. All of the above - Spark plug makes use of which of the following materials for insulation ?
A. Porcelain
B. Slate
C. Asbestos
D. Glass
