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N1 Engineering Science|The Easy Way! 129 Exercise 6.11 1. Define temperature coefficient of resistance.


2. What influence will an increase in temperature have on the resistance of a conductor?


3. What influence will an increase in temperature have on the resistance of an insulator?


4. Name one material that has a negative temperature coefficient of resistance. 5. Name one material that has a positive temperature coefficient of resistance.


6. Te resistance of a length of platinum wire is 15 ohms at 0 °C. Determine the resistance of the platinum wire at 100 °C. Take the temperature coefficient of resistance of platinum as 0,000 2/°C at 0 °C.


7. What effect will an increase in temperature have on the resistance of the following; 7.1 copper, 7.2 an insulator, and 7.3 a conductor?


8. Te field coil of a motor has a resistance of 20 ohms at 0 °C. Calculate the resistance of the coil at 36 °C if the temperature coefficient of resistance of copper is 0,004 26/°C at 0 °C.


9. A coil of copper wire has a resistance of 20 ohms at 0 °C. Calculate the resistance at 50 °C if the temperature coefficient of resistance of copper is 0,004 26/°C at 0 °C.


(23,07 ohms) (24,26 ohms)


10. A field coil made of copper wire, for a dc motor has a resistance of 50 ohms at 0 °C. Calculate the resistance at 60 °C if the temperature coefficient of resistance of copper is 0,004 26/°C at 0 °C.


11. A coil of copper wire has a resistance of 80 ohms at 0 °C. Calculate the resistance at 50 °C if the temperature coefficient of resistance of copper is taken as 0,004 3/°C at 0 °C.


(62,78 ohms) (97,2 ohms)


12. A coil made of copper wire has a resistance of 10 ohms at 0 °C. Calculate the resistance at 50 °C. Assume the temperature coefficient of resistance of copper to be 0,004 26/°C at 0 °C.


13. A coil of wire has a resistance of 120 ohms at 0 °C. Calculate the resistance at 36 °C if the wire has a temperature coefficient of resistance of 0,006 1/°C at 0 °C.


(12,13 ohms) (146,4 ohms)


14. Te temperature coefficient of resistance of the conductor of a coil for an electromagnet is 0,004 5/°C at 0 °C. At 0 °C the resistance of the coil is 32 ohms. Calculate the resistance at 45 °C.


(38,48 ohms) (15,3 ohms)


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