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The secondary coil of a transformer has 1500 turns and 10Ohm resistance. The primary coil has 1kOhm resistance. How many turns does the primary coil have?

  • 15,000.
  • 1,500,000.
  • 150,000

Explanation from PART66Online

Impedance transforms as the square of the turns ratio, so Np/Ns equals the square root of the impedance ratio. Here that is the square root of 1000/10, which is the square root of 100, equal to 10. The primary therefore has 10 x 1500 = 15,000 turns. The much larger options come from squaring the ratio instead of taking its root.

F

Faiz0108 asked · 19 Jul 2013

How does the answer comes to 15000?

Community Comments (4)

P
PART66Online 19 Jul 2013
Hey!

turn ratio = square_root(impendance ratio)
T
tsukiyo92 31 Jul 2014
Then it should write 10 ohm IMPEDANCE instead of resistance ? its kind of misleading.
T
ta2x 14 Apr 2019
square_root(1000/10)=10*1500=15000 turns primary
F
Fabioscotto 25 Sep 2019
The O of Ohm seems lile a 0

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