current-electricity Question 21
Question: Q. 10. Draw a plot showing the variation of resistivity of a (i) conductor and (ii) semiconductor, with the increase in temperature.
How does one explain this behaviour in terms of number density of charge carriers and the relaxation time? U [Delhi Comptt. I, II, III 2014]
In conductors, average relaxation time decreases with increase in temperature, resulting in an increase in resistivity.
In semiconductors, the increase in number density (with increase in temperature) is more than the decrease in relaxation time; the net result is, therefore, a decrease in resistivity.
[CBSE Marking Scheme 2014]
Q. 11. Draw a graph showing variation of resistivity with temperature for nichrome. Which property of nichrome is used to make standard resistance coils ?
U [O.D. Comptt. I, II, III, 2013]
Show Answer
Solution:
Ans. At low temperature (or zero), the resistivity increases as a higher power of temperature. Then, it linearly increases with increase in temperature.
Resistivity Vs. temperature (nichrome)
[CBSE Marking Scheme 2013]
