Q1. [4] § 11.7 HEATING EFFECT OF ELECTRIC CURRENT
Swati, a class 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.
Read the following passage and answer the questions that follow :
- (a) Describe the cause of heating in the above-mentioned case. [1]
- (b) A current I flows through a resistor of resistance R when the potential difference across it is V. Applying Ohm's law, write the formula for amount of heat produced by the resistor in time t. [1]
- (c) Answer (i) or (ii): [2]
Previously asked in CBSE board exam
2026 31/2/1 Q38
Generated by claude-sonnet-4-6 · 2026-06-15 06:42 · grounding stimulus
I notice sub-question (c) is incomplete — it mentions "Answer (i) or (ii)" but neither option is provided. I'll answer (a) and (b) fully, and note the gap for (c).
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Model Answer
(a) The heat felt near the refrigerator is due to the heating effect of electric current. The compressor motor and condenser coils carry electric current; as current flows through the resistance of these components, electrical energy is converted into heat energy, which is released into the surroundings.
(b) By Ohm's law, $V = IR$.
Heat produced is given by Joule's law of heating:
$$H = VIt = I^2Rt = \frac{V^2}{R}t$$
(c) (Sub-question (c) appears incomplete — options (i) and (ii) were not provided. Please supply them for a complete answer.)
Source: Chapter — Effects of Electric Current (Electricity), NCERT Class 10 Science
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Explanation
- (a) Examiners expect you to name the phenomenon ("heating effect of electric current") and briefly explain that electrical energy converts to heat in the resistive parts of the refrigerator circuit.
- (b) You must show the derivation starting from $V = IR$ and arrive at all three equivalent forms of $H = I^2Rt$. Writing all three forms earns full credit.
- (c) Sub-question (c) is missing from the prompt. In the actual exam, it likely asks you to compare series vs. parallel heating, or calculate heat/power — answer whichever option (i)/(ii) is printed in your paper.
If a question refers to an image, map, graph or diagram that is not shown here, find the actual CBSE question paper on the CBSE website:
cbse.gov.in.