Answer:
975.28 W.
Explanation:
Using,
R' = R(1+αΔt)....................... Equation 1
Where R' = Resistance at the final temperature, R = Resistance at the initial temperature, α = temperature coefficient of resistivity of Nichorome, Δt = Temperature rise.
Given: R = 9 Ω, α = 0.0004/°C, Δt = 1090-20 = 1070 °C
Substitute into equation 1
R' = 9(1+0.0004×1070)
R' = 9(1.428)
R' = 12.862 Ω.
Note: Operating wattage of the heater means the operating power of the heater
The power of the heater is given as,
P = V²/R'...................... Equation 2
Where P = Operating wattage of the heater, V = Voltage, R' = Operating resistance.
Given: V = 112 V, R' = 12.862 Ω
Substitute into equation 2
P = 112²/12.862
P = 975.28 W.
