Current Electricity Question 18
Question 18 - 2024 (30 Jan Shift 1)
An electric toaster has resistance of $60 \Omega$ at room temperature $\left(27^{\circ} \mathrm{C}\right)$. The toaster is connected to a $220 \mathrm{~V}$ supply. If the current flowing through it reaches $2.75 \mathrm{~A}$, the temperature attained by toaster is around : (if $\alpha=2 \times 10^{-4} /{ }^{\circ} \mathrm{C}$ )
(1) $694^{\circ} \mathrm{C}$
(2) $1235^{\circ} \mathrm{C}$
(3) $1694^{\circ} \mathrm{C}$
(4) $1667^{\circ} \mathrm{C}$
Show Answer
Answer: (3)
Solution:
$\mathrm{R}{\mathrm{T}=27}=60 \Omega, R{T}=\frac{220}{2.75}=80 \Omega$
$\mathrm{R}=\mathrm{R}_{0}(1+\alpha \Delta \mathrm{T})$
$80=60\left[1+2 \times 10^{-4}(\mathrm{~T}-27)\right]$
$\mathrm{T} \approx 1694^{\circ} \mathrm{C}$
