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Science · 2026 · 3 marks
CBSE 2026 · Region 3 · Set 1 · Q36
(a) Name a device which is used to: (i) Maintain a constant potential difference in a circuit. (ii) Change the electric current in an electric…
(a)
Name a device which is used to :
(i)
Maintain a constant potential difference in a circuit.
(ii)
Change the electric current in an electric circuit.
(b)
When the potential difference between the terminals of an electric heater is $\displaystyle 110$ V, a current of $\displaystyle 5$ A flows through it. What will be the value of current flowing through it when the potential difference is increased to $\displaystyle 220$ V ?
Marking-scheme solution
(a) (i) Battery / Electric cell
(ii) Rheostat / Variable resistance
(b) Resistance of the heater, \(\displaystyle \mathrm{R}=\frac{\mathrm{V}}{\mathrm{I}}\)
\[\begin{aligned}
& \mathrm{R}=\frac{110}{5} \\
& \mathrm{R}=22 \Omega
\end{aligned}
\]
Current through the heater, \(\displaystyle \mathrm{I}^{\prime}=\frac{\mathrm{V}^{\prime}}{\mathrm{R}}\)
\[\begin{aligned}
& =\frac{220}{22} \\
& =10 \mathrm{~A}
\end{aligned}
\]
Alternate answer for (b):According to Ohm's law, potential difference is directly proportional to current.
When the potential difference is doubled, current will also be doubled. So, value of current will be 10A.
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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.