A. voltage variation
B. thermostat
C. auto-transformer
D. series-parallel operation
Related Mcqs:
- By which of the following methods the temperature inside arc nace can be varied ?
A. By disconnecting some of the heating elements
B. By varying the operating voltage
C. By varying the current through heating elements
D. By any of the above method - In resistance heating highest working temperature is obtained from heating elements made of_____________?
A. nickel copper
B. nichrome
C. silicon carbide
D. silver - The temperature inside a furnace is usually measured by which of the following ?
A. Optical pyrometer
B. Mercury thermometer
C. Alcohol thermometer
D. Any of the above - Which of the following insulating materials was suitable for low temperature applications ?
A. Asbestos paper
B. Diatomaceous earth
C. 80 percent magnesia
D. Cork - Which of the following devices is necessarily required for automatic temperature control in a furnace ?
A. Thermostat
B. Thermocouple
C. Auto-transformer
D. Heating elements of variable resis-tance material - Resistance variation method of temperature control is done by connecting resistance elements in_____________?
A. series
B. parallel
C. series-parallel connections
D. star-delta connections
E. all of the above ways - Which of the following methods is used to control temperature in resistance furnaces ?
A. Variation of resistance
B. Variation of voltage
C. Periodical switching on and off of the supply
D. All of the above methods - Properly of low temperature co-eflficient of heating element is desired due to which of the following reasons ?
A. To avoid initial rush of current
B. To avoid change in kW rating with temperature
C. Both (A) and (B)
D. Either (A) or (B) - In a resistance furnace the atmosphere is_____________?
A. oxidizing
B. deoxidising
C. reducing
D. neutral - Radiations from a black body are proportional to____________?
A. T1
B. T2
C. T3
D. T*
