Estimate the design-stage uncertainty in determining the voltage drop across an electric heating element. the device has a nominal resistance of 30 ? and power rating of 500 w. available is an ohm meter (accuracy: within 0.5%; resolution: 1 ? ) and ammeter (accuracy: within 0.1 % ; resolution: 100 ma). recall e=ir hint: e=ir or in terms of power, p=pr

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.