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

• 1. Coreless transformers
• 2. Current transformers
• 3. Motor-generator set
• 4. Multi-phase transformer

Question: The temperature inside a furnace is usually measured by which of the following ?

• 1. Optical pyrometer
• 2. Mercury thermometer
• 3. Alcohol thermometer
• 4. Any of the above

Question: Which of the following insulating materials was suitable for low temperature applications ?

• 1. Asbestos paper
• 2. Diatomaceous earth
• 3. 80 percent magnesia
• 4. Cork

Question: The material of the heating element for a furnace should have___________?

• 1. lower melting point
• 2. higher temperature coefficient
• 3. high specific resistance
• 4. all of the above

Question: In an electric room heat convector the method of heating used is______________?

• 1. arc heating
• 2. resistance heating
• 3. induction heating
• 4. dielectric heating

Question: Induction furnaces are employed for which of the following ?

• 1. Heat treatment of castings
• 2. Heating of insulators
• 3. Melting aluminium
• 4. None of the above

Question: Which of the following will happen if the thickness of refractory wall of furnace is increased ?

• 1. Heat loss through furnace wall will increase
• 2. Temperature inside the furnace will fall
• 3. Temperature on the outer surface of furnace walls will drop
• 4. Energy consumption will increase

Question: A non-dimensional number generally associated with natural convection heat transfer is____________?

• 1. Prandtl number
• 2. Grashoff number
• 3. Pecelet number
• 4. Nusselt number

Question: Induction heating process is based on which of the following principles ?

• 1. Thermal ion release principle
• 2. Nucleate heating principle
• 3. Resistance heating principle
• 4. Electro-magnetic induction princi¬ple

Question: The process of heat transfer during the reentry of satellites and missiles, at very high speeds, into earth’s atmosphere is known as_______________?

• 1. ablation
• 2. radiation
• 3. viscous dissipation
• 4. irradiation