By which of the following methods the temperature inside arc nace can be varied ?

Related Mcqs:

1. 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...

2. 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...

3. Due to which of the following reasons it is desirable to have short arc length ?

   A. To achieve better heating B. To increase the life of roof refractory C. To have better stirring action D. To reduce problem of oxidation E. All of the above...

4. In direct arc furnace, which of the following has high value ?

   A. Current B. Voltage C. Power factor D. All of the above...

5. Direct arc furnaces have which of the following power factors ?

   A. Unity B. Low, lagging C. Low, leading D. Any of the above...

6. The electrode of a direct arc furnace is made of____________?

   A. tungsten B. graphite C. silver D. copper...

7. In arc furnace the function of choke is______________?

   A. to stabilize the arc B. to imprpve, power factor C. to reduce severity of the surge D. none of the above...

8. It is desirable to operate the arc furnaces at power factor of_____________?

   A. zero B. 0.707 lagging C. unity D. 0.707 leading...

9. Which of the following methods of heating is not dependent on the frequency of supply ?

   A. Induction heating B. Dielectric heating C. Electric resistance heating D. All of the above...

10. Which of the following heating methods has maximum power factor ?

    A. Arc heating B. Dielectric heating C. Induction heating D. Resistance heating...