A certain toaster has a heating element made of Nichrome resistance wire. When t

Question

A certain toaster has a heating element made of Nichrome resistance wire. When the toaster is first connected to a 140-V source of potential difference (and the wire is at a temperature of 20.0°C), the initial current is 1.80 A, but the current begins to decrease as the resistive element warms up. When the toaster reaches its final operating temperature, the current has dropped to 1.53 A. (a) Find the power the toaster converts when it is at its operating temperature. W (b) What is the final temperature of the heating element? °C

Explanation / Answer

(a) power at operating temperature =voltage*current=140*1.53=214.2 W

(b) resistance relation with temperature is given by

R=Ro(1+a*(temperature difference))

R=140/1.53=91.50 ohm

Ro=140/1.80=77.78

a=0.0004 for nichrome

91.50=77.78(1+0.0004(temperature difference))

temperature difference comes out to be =440.98

final temperature=20+440.98=460.98 degree celcius

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