Direct arc furnaces have which of the following power factors ?

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

Which of the following is an advantage of eddy current heating ?

A. The amount of heat generated can be controlled accurately
B. Heat at very high rate can be gene-rated
C. The area of the surface over which heat is produced can be accurately controlled
D. All of the above

Radiant heating is used for which of the following ?

A. Annealing of metals
B. Melting of ferrous metals
C. Heating of liquids in electric kettle
D. Drying of paints and varnishes

For radiant heating around 2250°C, the heating elements are made of____________?

A. Copper alloy
B. Carbon
C. Tungsten alloy
D. Stainless steel alloy

The electrode of a direct arc furnace is made of____________?

A. Tungsten
B. Graphite
C. Silver
D. Copper

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

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

In a domestic cake baking oven the temperature is controlled by________________?

A. Voltage variation
B. Thermostat
C. Auto-transformer
D. Series-parallel operation

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

In an electric press mica is used_____________?

A. As an insulator
B. As a device for power factor improvement
C. For dielectric heating
D. For induction heating

By the use of which of the following, high frequency power supply for induction furnaces can be obtained ?

A. Coreless transformers
B. Current transformers
C. Motor-generator set
D. Multi-phase transformer