Which of the following devices is necessarily required for automatic temperature control in a furnace?

Radiations from a black body are proportional to

A. T

B. T²

C. T³

D. T⁴

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)

The material of the heating element for a furnace should have

A. Lower melting point

B. Higher temperature coefficient

C. High specific resistance

D. All of the above

In induction heating __________ is abnormally high.

A. Phase angle

B. Frequency

C. Current

D. Voltage