Assignment:
Question 1. How long should a copper wire 0.4mm in diameter be for it to have a resistance of 10ohms? The resistivity of copper is 1.7 x 10-8 Q-m.
Question 2. An iron wire has a resistance of 0.20ohms at 20°C and a resistance of 0.30ohms at 110°C. Find the temperature coefficient of resistance of the iron used in the wire.
Question 3. A 75-W hall light is left on continuously. At $0.09 per kilowatt-hour, find the cost per week.
Provide complete and step by step solution for the question, use formulas.