CBSE 2023 · Region 5 · Set 2 · Q28 · 3 marks
The primary coil having $\displaystyle \mathrm{N}_{\mathrm{p}}$ turns of an ideal transformer is supplied with an alternating voltage $\displaystyle \mathrm{V}_{\mathrm{p}}$. Obtain an expression for the voltage $\displaystyle \mathrm{V}_{\mathrm{s}}$ induced in its secondary coil having $\displaystyle \mathrm{N}_{\mathrm{s}}$ turns. Mention two main sources of power loss in real transformers.
Marking-scheme solution
Obtaining an expression for voltage in secondary coil ($\displaystyle 2$) Two main sources of power loss \(\displaystyle \left(\frac{1}{2}+\frac{1}{2}\right)\) When alternating voltage \(\displaystyle \mathrm{V}_{\mathrm{P}}\) is supplied to the primary coil, an emf is induced in this coil.
\[\epsilon_{\mathrm{p}}=-\mathrm{N}_{\mathrm{p}} \frac{d \phi}{d t}=\mathrm{V}_{\mathrm{p}}
\] \(\displaystyle \frac{1}{2}\) Which causes an induced emf in secondary coil
\[\epsilon_{\mathrm{s}}=-\mathrm{N}_{\mathrm{s}} \frac{d \phi}{d t}
\]
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CBSE Class 12 Physics past-paper question from the 2023board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.