answers for points (a) What is the voltage output of a transformer used for rech

Question

answers for points

(a) What is the voltage output of a transformer used for rechargeable flashlight batteries, if its primary has 525 turns, its secondary 8 turns, and the input voltage is 119V?
(No Response) V
(b) What input current is required to produce a 4.00 A output?
(No Response) mA
(c) What is the power input?
(No Response) W

A large power plant generates electricity at 12.0 kV. Its old transformer once converted the voltage to 400 kV. The secondary of this transformer is being replaced so that its output can be 485 kV for more efficient cross-country transmission on upgraded transmission lines.

(a) What is the ratio of turns in the new secondary to turns in the old secondary?
(No Response)
(b) What is the ratio of new current output to old output (at 400 kV) for the same power?
(No Response)
(c) If the upgraded transmission lines have the same resistance, what is the ratio of new line power loss to old?
(No Response)

Explanation / Answer

a) Np / Ns = Vi / Vo

525 / 8 = 119 / Vo

Vo = 1.81 Volt

b) Np Ip = Ns Is

525 x Ip = 8 x 4A

Ip = 0.061 A

c) P = Vi * Ip = 119 * 0.061 = 7.25 W

--------------------------

a) Np / Ns = Vi / Vo

In old transformer
Np / Ns = 12 / 400 ....(i)

In new ,

Np / Ns' = 12/485 ....(ii)

(i) / (ii) => Ns' / Ns = 485 / 400 = 1.2125

b) In old transformer
Np / Ns = Io / Ii ....(i)

In new ,

Np / Ns' = Io' / Ii .... (ii)

(ii) / (i) => Io' / Io = Ns / Ns' = 1/1.2125 = 0.825

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