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

• 1. By disconnecting some of the heating elements
• 2. By varying the operating voltage
• 3. By varying the current through heating elements
• 4. By any of the above method

Question: In induction heating ___________ is abnormally high?

• 1. phase angle
• 2. frequency
• 3. current
• 4. voltage

Question: In a resistance furnace the atmosphere is_____________?

• 1. oxidizing
• 2. deoxidising
• 3. reducing
• 4. neutral

Question: Which of the following has the highest value of thermal conductivity ?

• 1. Water
• 2. Steam
• 3. Sold ice
• 4. Melting ice

Question: Heat transfer by condition will not occur when____________?

• 1. bodies are kept in vacuum
• 2. bodies are immersed in water
• 3. bodies are exposed to thermal radiations
• 4. temperatures of the two bodies are identical

Question: Heat is transferred simultaneously by condition, convection and radiation_____________?

• 1. inside boiler furnaces
• 2. during melting of ice
• 3. through the surface of the insulted pipe carrying steam
• 4. from refrigerator coils to freezer of a refrigerator

Question: For the transmission of heat from one body to another__________?

• 1. temperature of the two bodies must be different
• 2. both bodies must be solids
• 3. both bodies must be in contact
• 4. at least one of the bodies must have some source of heating

Question: A perfect black body is one that_____________?

• 1. transmits all incident radiations
• 2. absorbs all incident radiations
• 3. reflects all incident radiations
• 4. absorbs, reflects and transmits all incident radiations

Question: When a body reflects entire radiation incident on it, then it is known as____________?

• 1. white body
• 2. grey body
• 3. black body
• 4. transparent body

Question: is used for heating non-conducting materials?

• 1. Eddy current heating
• 2. Arc heating
• 3. Induction heating
• 4. Dielectric heating