An electric toaster has resistance of 60 Ω at room temperature (27ºC). The toaster is connected to a 220 V supply. If the current flowing through it reaches 2.75 A, the temperature attained by toaster is around : (if α = 2 × 10⁻⁴ /ºC)
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Question

An electric toaster has resistance of 60 Ω at room temperature (27ºC). The toaster is connected to a 220 V supply. If the current flowing through it reaches 2.75 A, the temperature attained by toaster is around : (if α = 2 × 10⁻⁴ /ºC)

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G1 Physics · Accepted Answer

At 27ºC: R₀ = 60 Ω At final temperature: R = V/I = 220/2.75 = 80 Ω Using, R = R₀[1 + α(T - 27)] 80 = 60[1 + 2 × 10⁻⁴(T - 27)] 80/60 - 1 = 2 × 10⁻⁴(T - 27) 1/3 = 2 × 10⁻⁴(T - 27) T - 27 ≈ 1666.7 T ≈ 1694ºC