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PRACTICE / Transformers

Two loads behind one transformer

An ideal transformer has five times as many primary turns as secondary turns. A 100 V RMS sinusoidal supply feeds the primary. Two 20 Ω resistors are connected in parallel across the secondary.

What RMS current does the primary draw?

Organize the givens & assumptions
  • Nₚ/Nₛ = 5
  • Primary voltage: 100 V RMS
  • Secondary load: two 20 Ω resistors in parallel

Ideal lossless transformer with negligible magnetizing current; resistive load; all specified and requested AC magnitudes are RMS values.

  1. A2.0 A2.0\ \mathrm A
  2. B10 A10\ \mathrm A
  3. C0.20 A0.20\ \mathrm A
  4. D0.40 A0.40\ \mathrm A

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