Page 1 :
Relation between Res, and the Temperature 1. Increase in resistance, , temperature., , It has been found, conductors made from a P, the rise in temperature,, , For example, the filament Of an elec., bulb is made from pure tungsten. The reg:, of this filament is far higher, when the byj,, glows, than its resistance at room temperaturs, , 2. Very little or no change in resistance wit,, rise in temperature., , In case of metallic alloys, the resistance, does not increase with the rise in temperature,, l.é, increase in resistance is not appreciable., , E.g., Manganin, Eureka, German silver, Constantan are the alloys, whose resistance, almost remains same, with the rise in, temperature., , These alloys are used for making standaté, resistances for resistance boxes, rheostats, et, 3. Decrease in resistance with the rise ip, , temperature. bes, , Resistance of carbon filament bulb #®, with the rise in temperature. i, , Resistance of ionic compounds decreas’, on fusion (melting) and they start con |, electricity. Resistance of vulcanised rue}, drops by 25%, when heated from 0°C to 24*, , With the te, , ure metal, rises ig, , , , sgt