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Science · 2026 · 3 marks
CBSE 2026 · Region 3 · Set 3 · Q37
(a) State Ohm's law and justify that V - I graph for Ohm's law will always be a straight line passing through the origin. (b) The figure shows V - I…
(a)
State Ohm's law and justify that V - I graph for Ohm's law will always be a straight line passing through the origin.
(b)
The figure shows V - I graphs for two identical wires A and B having the same length and area of cross-section, but made of different materials. Which of these wires will be more suitable for making the heating element of an electric heater and why ?
Marking-scheme solution
(a)
Ohm's law - The potential difference 'V' across the ends of given metallic wire in an electric circuit is directly proportional to the current flowing through it, provided its temperature remains same.
\(\displaystyle V \propto I \frac{V}{I}=\) Constant for all corresponding values of V and I.
/ The same value of \(\displaystyle \frac{V}{I}\) is obtained from the graph for all corresponding points of V and I.
(b)
Wire B.
The slope of B is higher, so it has higher resistance/ resistivity.
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CBSE Class 10 Science past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.