Question

The heating element of an electirc toaster is of nichrome. When a vary small current passes through it, at room temperrature `27^@C`, its resistance is `75.3Omega`. When toaster is connected to a 230V supply, the current settles after a few seconds to a steady value of 2.68A. What is the steady temperature of nichrome element? The temperature coefficient of resistance of nichrome over averged temperature range is `1.7xx10^(-4)^(@)C^(-1)`.

Answer 1

Here, `R_(27) =75.3 Omega`,
`alpha=1.7xx10^(-4).^(@)C^(-1),V=230 V, I=2.68A`
`R_(t) =230/2.68 =85.82 Omega`,
As, `t_(2)-t_(1) =(R_(1)-R_(1))/(R_(1)xxalpha)`
`:. t -27 = (R_(1)-R_(27))/(R_(27) xx alpha)=(85.82-75.3)/(75.3xx1.7xx10^(-4))=822^@C`
or `t=822 +27 =849^@C`