la) Explain what is meant by the temperature coefficient of resistance of a material.< A conductor has a resistance of R1 ohms at 01°C, and consists of copper with a temperature coefficient of resistance a referred to 0°C. Find an expression for the resistance R2 of the conductor at temperature 02°C.< The coil of a transformer has a resistance of 2.5 2 at 15°C. By how much will the resistance increase if the transformer attains an average temperature of 45°C when it is loaded? Take a = 0.00428/°C at 0°C. (Ans. 0.392).< (10 marks) lb) Two batteries connected in parallel are used as an emergency supply in a building. The first battery has an EMF of 120 V with an internal resistance of 10 Q2. The second battery has an EMF of 150 V with an internal resistance of 20 Q2. An emergency incandescent lamp with a nominal power of 288 watts at 120 V is supplied by the two batteries. Calculate the current through the lamp and the power consuming by the lamp based on Thevenin's theorem. (Ans. 2.3A, 264.5W).< (10 marks)