141. In a domestic cake baking oven, the temperature is controlled by
A. series parallel operation
B. auto transformer
C. thermostat
D. voltage variation

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142. Thermal conductivity is least for
A. air
B. water
C. glass
D. copper

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143. Method of heating which likely gives leading power factor is
A. electric arc
B. induction heating
C. dielectric heating
D. resistance heating

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144. In an electric press, mica is used
A. for dielectric heating
B. for induction heating
C. as an insulator
D. as a device for power factor improvement

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145. Methods which is suitable for the heating of conducting medium is
A. Radiant heating
B. Eddy current heating
C. Induction heating
D. Indirect arc heating

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146. In dielectric heating, current flows through
A. metallic conductor
B. ionic discharge between dielectric medium and metallic conductor
C. dielectric
D. air

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147. Desirable property of resistance heating element materials is
A. High resistivity
B. High melting point
C. Low temperature coefficient
D. All of these

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