Q3) A 1200-W iron is left on the ironing board with its base exposed to the air. About 85 percent of the heat generated in the iron is dissipated through its base whose surface area is 150 cm², and the remaining 10 percent through other surfaces. Assuming the heat transfer from the surface to be uniform, determine (a) the amount of heat the iron dissipates during a 2-hour period, in kWh, (b) the heat flux on the surface of the iron base, in W/m², and (c) the total cost of the electrical energy consumed during this 2-hour period. Take the unit cost of electricity to be $ 0.07/kWh. Ans: (a) 2.4 kWh (b) 72 kW/m² (c) $ 0.17

Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
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Q3) A 1200-W iron is left on the ironing board with its base exposed to the air.
About 85 percent of the heat generated in the iron is dissipated through its base
whose surface area is 150 cm², and the remaining 10 percent through other
surfaces. Assuming the heat transfer from the surface to be uniform, determine (a)
the amount of heat the iron dissipates during a 2-hour period, in kWh, (b) the
heat flux on the surface of the iron base, in W/m², and (c) the total cost of the
electrical energy consumed during this 2-hour period. Take the unit cost of
electricity to be $ 0.07/kWh.
Ans: (a) 2.4 kWh
(b) 72 kW/ m²
(c) $ 0.17
Transcribed Image Text:Q3) A 1200-W iron is left on the ironing board with its base exposed to the air. About 85 percent of the heat generated in the iron is dissipated through its base whose surface area is 150 cm², and the remaining 10 percent through other surfaces. Assuming the heat transfer from the surface to be uniform, determine (a) the amount of heat the iron dissipates during a 2-hour period, in kWh, (b) the heat flux on the surface of the iron base, in W/m², and (c) the total cost of the electrical energy consumed during this 2-hour period. Take the unit cost of electricity to be $ 0.07/kWh. Ans: (a) 2.4 kWh (b) 72 kW/ m² (c) $ 0.17
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