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Science · 2022 · 3 marks
CBSE 2022 · Region 1 · Set 3 · Q10
For a heater, rated 4 kW and 220 V, calculate the following: (a) The current (b) Energy consumed in 2 hours (c) If 1 kWh is priced at ₹ 4 · 50, then…
For a heater, rated $\displaystyle 4$ kW and $\displaystyle 220$ V, calculate the following:
(a)
The current
(b)
Energy consumed in $\displaystyle 2$ hours
(c)
If $\displaystyle 1$ kWh is priced at ₹ $\displaystyle 4 \cdot 50$, then the cost of energy consumed
Marking-scheme solution
Given : \(\displaystyle P=4 \mathrm{~kW}=4000 \mathrm{~W}\)
\(\displaystyle V=220 \mathrm{~V}\)
(a) \[\begin{aligned}
& P=V I \\
& I=\frac{P}{V}=\frac{4000 \mathrm{~W}}{220 \mathrm{~V}}=18 \cdot 18 \mathrm{~A}
\end{aligned}
\]
(b) \[\begin{aligned}
E & =P X t \\
& =4 \mathrm{~kW} \times 2 \mathrm{~h}=8 \mathrm{kWh}
\end{aligned}
\]
(c) Cost of \(\displaystyle 1 \mathrm{~kW}=₹ 4 \cdot 50\) Then \(\displaystyle 8 \mathrm{kWh}=8 \times 4 \cdot 50=₹ 36 \cdot 0\)
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CBSE Class 10 Science past-paper question from the 2022 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.