A heat lamp emits infrared radiation whose rms electric field is Erms = 3800 N/C

Question

A heat lamp emits infrared radiation whose rms electric field is Erms = 3800 N/C. (a) What is the average intensity of the radiation? (b) The radiation is focused on a person's leg over a circular area of radius 4.0 cm. What is the average power delivered to the leg? (c) The portion of the leg being radiated has a mass of 0.35 kg and a specific heat capacity of 3500 J/(kg·C°). How long does it take to raise its temperature by 2.8 C°? Assume that there is no other heat transfer into or out of the portion of the leg being heated.

I got the answer of a) 38.33 W/m^2
b) 192.61 W please help me find C) ???

Explanation / Answer

(c). mass m = 0.35 kg Specific heat c = 3500 J / kg oC temperature raise dt = 2.8 oC amount of heat required to raise the portion of leg to dt temperature is Q = mc dt             Q = 3430 J we know avergae power delivered to the leg P = 192.61 W therefore required time t = E / P                                       = 17.808 s

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