Power in an Electric Heater An electric heater is constructed by applying a potential difference of 120 V across a Nichrome wire that has a total resistance of 8.10 Ω. Find the current carried by the wire and the power rating of the heater. SOLUTION Conceptualize As discussed in the example The Resistance of a Nichrome Wire, Nichrome wire has high resistivity and is often used for heating elements in toasters, irons, and electric heaters. Therefore, we expect the power delivered to the wire to be relatively Correct: Your answer is correct. . Categorize We evaluate the power from P = I2R = (ΔV)2 R , so we categorize this example as Correct: Your answer is correct. problem. Analyze Use this equation to find the current (in A) in the wire: I = ΔV R = 14.1 Incorrect: Your answer is incorrect. A Find the power rating (in kW) using the expression P = I2R: P = I2R = 1.69 Incorrect: Your answer is incorrect. kW EXERCISE Consider a heater rated at 120 V with power 3.2 kW. Hint (a) What is the resistance of the heater (in Ω), and the current (in A) when it is under normal operation? R = Ω I = A (b) If we connect it a 240 V source, assuming that it still works, what will be the actual power consumption now (in kW)? kW