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Alternating Current question

2021 · 24 Feb · Shift 1 · Q68
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Alternating Current question

2021 · 24 Feb · Shift 1 · Q68

JEE MainPhysicsAlternating CurrentNumerical+4 / −1
A common transistor radio set requires 12 V (D.C.) for its operation. The D.C. source is constructed by using a transformer and a rectifier circuit, which are operated at 220 V (A.C.) on standard domestic A.C. supply. The number of turns of secondary coil are 24, then the number of turns of primary are ‾\underline{\hspace{2cm}}​.
Numerical answer
View written solutionFree

Correct answer: 440

  1. Use transformer relation

For an ideal transformer,

VsVp=NsNp\frac{V_s}{V_p} = \frac{N_s}{N_p}Vp​Vs​​=Np​Ns​​

where:

  • Vp=220 VV_p = 220\,\text{V}Vp​=220V (A.C. input)
  • Vs=12 VV_s = 12\,\text{V}Vs​=12V (required output)
  • Ns=24N_s = 24Ns​=24
  • Np=?N_p = ?Np​=?
  1. Substitute the values

12220=24Np\frac{12}{220} = \frac{24}{N_p}22012​=Np​24​

  1. Solve for NpN_pNp​

Np=24×22012N_p = 24 \times \frac{220}{12}Np​=24×12220​

Np=2×220=440N_p = 2 \times 220 = 440Np​=2×220=440

  1. Final answer

The number of turns in the primary coil is

440\boxed{440}440​

  1. Comparison with stored answer

Stored correct answer = 440440440

So, the derived answer matches the stored answer.

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