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
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
The photo-electric effect occurs only when the incident light has more than a certain critical____________?
(A) intensity
(B) speed
(C) frequency
(D) wave length
Spark plug makes use of which of the following materials for insulation ?
(A) Porcelain
(B) Slate
(C) Asbestos
(D) Glass
___________ has the best damping properties?
(A) Diamond
(B) High speed steel
(C) Mild steel
(D) Cast iron
Which of the following is a semiconductor material ?
(A) Phosphorous
(B) Rubber
(C) Silicon
(D) Aluminium
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
Which of the following materials is the best conductor of electricity ?
(A) Tungsten
(B) Aluminium
(C) Copper
(D) Carbon
Thermocouples are mainly used for the measurement of_____________?
(A) temperature
(B) resistance
(C) eddy currents
(D) coupling co-efficient