CBSE 2024 · Region 2 · Set 3 · Q24 · 2 marks
An ac voltage $\displaystyle \mathrm{v}_{\mathrm{i}}=140 \sin (100 \pi \mathrm{t}) \mathrm{V}$ is applied to the primary coil having $\displaystyle 200$ turns, of an ideal transformer and it supplies a power of $\displaystyle 5$ kW . If the secondary coil has $\displaystyle 1000$ turns, find :(a)the output voltage,(b)the instantaneous voltage across the secondary coil, and(c)the current in the secondary coil. (Take $\displaystyle \sqrt{2}=1 \cdot 4$ )
An ac voltage $\displaystyle \mathrm{v}_{\mathrm{i}}=140 \sin (100 \pi \mathrm{t}) \mathrm{V}$ is applied to the primary coil having $\displaystyle 200$ turns, of an ideal transformer and it supplies a power of $\displaystyle 5$ kW . If the secondary coil has $\displaystyle 1000$ turns, find :
(a)
the output voltage,
(b)
the instantaneous voltage across the secondary coil, and
(c)
the current in the secondary coil. (Take $\displaystyle \sqrt{2}=1 \cdot 4$ )
Marking-scheme solution
(a)
$\displaystyle V_{P(\mathrm{rms})}=\frac{140}{\sqrt{2}}=\frac{140}{1.4}=100 \mathrm{~V}$
$\displaystyle \therefore V_{s}=\frac{N_{s}}{N_{p}} V_{p}=\frac{1000}{200} \times 100=500 \mathrm{~V}$
(b)
$\displaystyle v_{s}=500 \sqrt{2} \sin 100 \pi t=700 \sin 100 \pi t$
(c)
Power output $\displaystyle =$ Power input
$\displaystyle I_{s}=\frac{5000}{500}=10 \mathrm{~A}$
Alternating CurrentTransformersApplyvery_short_answermedium
More from Alternating Current
- An alternating current is given by I=I 0 cos (100 π) t. The least time the current takes to decrease from its…2025 · asked 3×
- A resistor of 30 Ω and a capacitor of 250/(π) μ F are connected in series to a 200 V, 50 Hz ac source.…2023 · asked 3×
- An inductor, a capacitor and a resistor are connected in series across an ac source of voltage. If the…2023 · asked 3×
- Assertion: A series LCR circuit behaves as a pure resistive circuit at resonance. Reason (R): At resonance, X…2025 · asked 3×
- How does the resistance differ from impedance? With the help of a suitable phasor diagram, obtain an…2023 · asked 3×
- Assertion: In an ideal step-down transformer, the electrical energy is not lost. Reason (R): In a step-down…2025 · asked 3×
- An ac voltage is given as v=14 sin (314 t) V. The average and the effective value of the voltage (in V ) over…2026 · asked 3×
- The figure shows the variation of capacitive reactance (X C) of two ideal capacitors of capacitances C 1 \& C…2026 · asked 3×
CBSE Class 12 Physics past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.