Fri May 18, 2012 By:

A Metallic coil connected to a 220V supply, has a resistance of 110 ohm(while hot.How long will it take this coil to heat 1Kg of water from 20 degree C to 70 degree C ? Assume that whole of heat produced by the coil is taken up by the water.Specific heat of water is 4186 J/Kg degree C.

Expert Reply
Mon May 21, 2012
heat  generated  by the coil of resistance 110 ohm = heat taken by water
V2/R  t=ms(T1-T2)
220x220/110   t=1 x4186(70-20)
t=475.68 s
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