A 500-W heating coil designed to operate from 110 V is made of Nichrome wire 0.500 mm in diameter. (a) Assuming the resistivity of the Nichrome remains constant at its 20.0°C value, find the length of wire used. (b) What If? Now consider the variation of resistivity with temperature. What power is delivered to the coil of part (a) when it is warmed to 1 200°C?

Consider the following. R Vba = 12 V (a) Find the current through the resistor in the figure above. (Take R = 6 02.) (b) If the resistor is made of carbon, what will its resistance be when its temperature is increased by 97.0 C°? (The temperature coefficient of resistivity for carbon is -5.0 x 10-4 (°C)-¹.) b

A Nichrome heating element in an oven has a resistance of 8.0 V at 20°C. (a) What is its resistance at 350°C? (b) What assumption did you have to make to obtain your answer to part (a)?

A 490-W heating coil designed to operate from 110 V is made of Nichrome wire 0.420 mm in diameter. (Assume ρ = 1.50  10-6 Ω · m, and α = 4.000  10-4(°C)−1 for Nichrome.) (a) Assuming the resistivity of the Nichrome remains constant at its 20.0°C value, find the length of wire used. m(b) Now consider the variation of resistivity with temperature. What power is delivered to the coil of part (a) when it is warmed to 1 200°C?

When an electric heater is turned on, the Nichrome heating element is at 0° C and draws a current of 18 A, with a potential difference of 120 V between the ends of the element. The element heats up to 795° C, with the potential difference constant. Find the final current. (The temperature coefficient of resistivity of Nichrome is 4.0  10-4 (°C)-1.)

A 360-W heating coil designed to operate from 110 V is made of Nichrome wire 0.510 mm in diameter. (Assume p = 1.50 x 10-6 2. m, and a = 4.000 x 10-4(°C)-1 for Nichrome.) (a) Assuming the resistivity of the Nichrome remains constant at its 20.0°C value, find the length of wire used. (b) Now consider the variation of resistivity with temperature. What power is delivered to the coil of part (a) when it is warmed to 1 200°C? Need Help? Read It

(a) A 35.1-m length of copper wire at 20.0°C has a radius of 0.23 mm. If a potential difference of 7.0 V is applied across the length of the wire, determine the current in the wire. (Use the values in the following table.) Resistivities and Temperature Coefficients of Resistivity for Various Materials (at 20°C) Material Resistivity(Ω · m) Temperature Coefficientof Resistivity [(°C)−1] Silver 1.59 ✕ 10−8 3.8 ✕ 10−3 Copper 1.7 ✕ 10−8 3.9 ✕ 10−3 Gold 2.44 ✕ 10−8 3.4 ✕ 10−3 Aluminum 2.82 ✕ 10−8 3.9 ✕ 10−3 Tungsten 5.6 ✕ 10−8 4.5 ✕ 10−3 Iron 10.0 ✕ 10−8 5.0 ✕ 10−3 Platinum 11 ✕ 10−8 3.92 ✕ 10−3 Lead 22 ✕ 10−8 3.9 ✕ 10−3 Nichromea 150 ✕ 10−8 0.4 ✕ 10−3 Carbon 3.5 ✕ 10−5 −0.5 ✕ 10−3 Germanium 0.46 −48 ✕ 10−3 Silicon 640 −75 ✕ 10−3 Glass 1010–1014   Hard rubber ≈1013   Sulfur 1015   Quartz (fused) 75 ✕ 1016   aA nickel–chromium alloy commonly used in heating elements.  ??A(b) If the wire is heated to 36.0°C while the 7.0-V potential difference is…

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(a) In the figure what value must R have if the current in the circuit is to be 1.3 mA? Take ₁ = 2.7 V, 8₂-5.3 V, and r₁ r2 = 3.9 Q. (b) What is the rate at which thermal energy appears in R? www.i R (a) Number (b) Number ww MI -48₂ i N Units Units <