A. Where lubrication is difficult or im-possible
B. Where corrosive chemical action exists
C. Where high temperature exists
D. All of the above
Related Mcqs:
- Carbon electrodes are not used in_______________?
A. GLS lamps
B. electric arc furnace
C. dry cells
D. cinema projectors - A carbon resistor contains_____________?
A. carbon crystals
B. solid carbon granules
C. pulverized coal
D. finely divided carbon black - Carbon rods are used in wet and dry cells because_____________?
A. carbon rod serves as conductor
B. carbon can resist the attack of battery acid
C. both (A) and (B)
D. either (A) or (B) - Carbon resistors are used extensively because they are____________?
A. easy to make
B. compact
C. inexpensive
D. all of the above reasons - The carbon percentage is least in__________________?
A. low carbon steel
B. wrought iron
C. cast iron
D. malleable iron - In thermocouples which of the following pairs is commonly used ?
A. Copper-constantan
B. Aluminium-tin
C. Silver-German silver
D. Iron-steel - Due to which of the following reasons aluminium does not corrode in atmosphere ?
A. Aluminium is a noble metal
B. Atmospheric oxygen can only diffuse very slowly through the oxide layer which is formed on the surface of aluminium
C. No reaction with oxygen occurs ft Any of the above - Which of the following high resistance materials has the highest operating temperature ?
A. Kanthal
B. Manganin
C. Nichrome
D. Eureka - Which of the following materials is used for making coils of standard resistances ?
A. Copper
B. Nichrome
C. Platinum
D. Manganin - Which of the following is a semiconductor material ?
A. Phosphorous
B. Rubber
C. Silicon
D. Aluminium
