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Science · 2026 · 4 marks
CBSE 2026 · Region 2 · Set 1 · Q38
Read the following passage and answer the questions that follow: Swati, a class 10 student, observes that when she passes close to the refrigerator…
Read the following passage and answer the questions that follow : Swati, a class $\displaystyle 10$ student, observes that when she passes close to the refrigerator in her kitchen, she feels the heat, although the things kept inside the refrigerator are cool.
(a)
Describe the cause of heating in the above-mentioned case.
(b)
A current $\displaystyle I$ flows through a resistor of resistance $\displaystyle R$ when the potential difference across it is $\displaystyle V$. Applying Ohm's law, write the formula for amount of heat produced by the resistor in time $\displaystyle t$.
(c)
(i)
Write any two practical applications of heating effect of electric current.
OR
(ii)
Define the commercial unit of electric energy and express it in Joules (J).
Marking-scheme solution
(a) A part of current is consumed into useful work and rest is expended in heat to raise the temperature of gadget.
(b) \[\begin{aligned}
& \mathrm{W}=\mathrm{V} \times \mathrm{Q}=\mathrm{VIt}=\mathrm{IR} \times \mathrm{It} \\
& \mathrm{H}=\mathrm{I}^{2} \mathrm{Rt}
\end{aligned} / \quad \frac{V^{2}}{R} \mathrm{t}
\]
(c) (i) Electric heater, Oven, Electric iron OR
(c) (ii) When $\displaystyle 1$ kilowatt of power is used for $\displaystyle 1$ hour then energy consumed is $\displaystyle 1$ kWh \(\displaystyle 1 \mathrm{kWh}=3.6 \times 10^{6} \mathrm{~J}\)
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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.