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Science · 2023 · 5 marks
CBSE 2023 · Region 1 · Set 1 · Q36
(a) An electric iron consumes energy at a rate of 880 W when heating is at the maximum rate and 330 W when the heating is at the minimum. If the…
(a)
An electric iron consumes energy at a rate of $\displaystyle 880$ W when heating is at the maximum rate and $\displaystyle 330$ W when the heating is at the minimum. If the source voltage is $\displaystyle 220$ V, calculate the current and resistance in each case.
(b)
What is heating effect of electric current ?
(c)
Find an expression for the amount of heat produced when a current passes through a resistor for some time.
Marking-scheme solution
(a)
When heating is at maximum rate.
Power, \(\displaystyle \mathrm{P}=880 \mathrm{~W}\)
Voltage, \(\displaystyle \mathrm{V}=220 \mathrm{~V}\)
Current, \(\displaystyle \mathrm{I}=\frac{\mathrm{P}}{\mathrm{V}}=\frac{880}{220}=4 \mathrm{~A}\)
Resistance, \(\displaystyle \mathrm{R}=\frac{\mathrm{V}}{\mathrm{I}}=\frac{220}{4}=55 \Omega\)
When heating is at minimum rate
Current, \(\displaystyle \mathrm{I}=\frac{\mathrm{P}}{\mathrm{V}}=\frac{330}{220}=\frac{3}{2}=1.5 \mathrm{~A}\)
Resistance, \(\displaystyle \mathrm{R}=\frac{\mathrm{V}}{\mathrm{I}}=\frac{220}{115}=146.6 \Omega\)
(b)
When electric current is passed through a resistor, electrical
(c)
\(\displaystyle \mathrm{H}=\mathrm{I}^{2} \mathrm{Rt} / \mathrm{H}=\mathrm{VIt}\)
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CBSE Class 10 Science past-paper question from the 2023 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.