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Physics · 2025 · 3 marks
CBSE 2025 · Region 2 · Set 2 · Q22
(a) Define resistivity of a conductor. Discuss its dependence on temperature of the conductor and draw a plot of resistivity of copper as a function…
(a)
Define resistivity of a conductor. Discuss its dependence on temperature of the conductor and draw a plot of resistivity of copper as a function of temperature.
(b)(i)
"A low voltage battery from which high current is required must have low internal resistance. "Justify.
(ii)
"A high voltage battery must have a large internal resistance. " Justify.
Marking-scheme solution
(a)
Resistivity is the resistance of a material of unit length having unit area of cross-section.
On increasing the temperature of a conductor, the resistivity increases.
(b)(i)
A low internal resistance allows large current to be drawn even at a low voltage.
(ii)
To limit the current.
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