An ac generator generating an emf is connected to a resistor. Draw a labelled graph of current (I)…
An ac generator generating an emf $e = 300 \sin(100\pi t)\text{V}$ is connected to a $100\,\Omega$ resistor.
(a)
Draw a labelled graph of current (I) flowing through it versus time (t). Draw one cycle only.
(b)
Calculate the average power consumed by the resistor.
(c)
Why ac is preferred to dc, though it has varying values whereas the latter has a fixed value?
(d)
State any one difference between a transformer used at the power generating station and the transformer in a city which is used to supply power to households.
Answer
Answer (b)
AIWritten by AI (gemini) - it can contain mistakes.
Average power $\langle P \rangle = \frac{I_0^2 R}{2} = \frac{3^2 \times 100}{2} = \frac{900}{2} = 450\text{ W}$.
Final answer: 450 W
Answer (c)
AIWritten by AI (gemini) - it can contain mistakes.
AC is preferred over DC for long-distance power transmission because AC voltages can be stepped up or down efficiently using transformers, which minimizes power loss ($I^2R$) during transmission.
Answer (d)
AIWritten by AI (gemini) - it can contain mistakes.
The transformer at a power generating station is a step-up transformer (to transmit power at high voltage and low current), whereas the transformer in a city supplying households is a step-down transformer (to lower voltage to safe levels like 220V).
From ISC 2027 Specimen Physics Paper 1, question 18(ii).