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Class 12
Physics
Current Electricity
a heating element using nichrome connected to a 23...

Question:
A heating element using nichrome connected to a 230 V supply draws an initial current of 3.2 A which settles after a few seconds to a steady value of 2.8 A. What is the steady temperature of the heating element if the room temperature is 27.0 °C? Temperature coefficient of resistance of nichrome averaged over the temperature range involved is 1.70 x 10^-4 °C ^-1.

Answer:

Supply voltage, V = 230 V

Initial current drawn, I₁ = 3.2 A

Initial resistance = R₁, which is given by the relation,

Steady state value of the current, I₂ = 2.8 A

Resistance at the steady state = R₂, which is given as

Temperature co-efficient of nichrome, α = 1.70 × 10 ^{- 4} °C ^{- 1}

Initial temperature of nichrome, T₁= 27.0°C

Study state temperature reached by nichrome = T₂

T₂ can be obtained by the relation for α,

Therefore, the steady temperature of the heating element is 867.5°C

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