Question

A transformer has 400 turns in the primary and 3600 turns in the secondary winding. When the primary is impressed with 240 volt, 9 ampere flow through its winding. What is the voltage in the secondary? If the transformer were 90% efficient, what would be the current in the secondary?​

Answer 1

Answer:

First we use the fact that the ratio of the voltage on the secondary and on the primary will be the same as the ratio of the number of turns of both coils,

⇒u=

u

1

u

2

=

N

1

N

2

We evaluate the unkown secondary voltage -

⇒u

2

=

N

1

N

2

u

1

We substitute the given values -

⇒u

2

=

500

10

×120v=2.4v

Hence, the answer is 2.4v.

Answer 2

Answer:

When a transformer which has 400 turns in the primary and 3600 turns in the secondary winding is impressed with 240 volt and 9 ampere through its primary winding then the voltage in the secondary will be 2120 volts. If the transformer is 90% efficient, the current in the secondary is 0.917 ampere.

Explanation:

Number of turns in the primary winding, N₁ = 400

Number of turns in the secondary winding, N₂= 3600

Voltage in the primary winding, V₁ = 240 V

Current in the primary winding, I₁ = 9 A

The transformer equation is given by,

                                    $\frac{{V_{2} } }{V_{1} }=\frac{N_{2} }{N_{1} }$

From this equation, we can calculate the voltage in the secondary winding as,

                                    $V_{2} =\frac{N_{2} }{N_{1} } V_{1}$

                                    $V_{2} = \frac{3600}{400} *240$

                               ∴   $V_{2} = 2120 V$

Now to calculate the current in the secondary winding, let's make use of the equation for the efficiency of the transformer.

Efficiency, η = (power in the output ÷ power in the input) × 100

Power is given by the equation, $P=VI$

∴ power in the output = V₂ × I₂ = 2120 × I₂

   Power in the input =V₁ × I₁= 240 × 9 = 2160

We know the efficiency of the transformer (η) as 90%

∴ η = 90

So we can rewrite the equation for efficiency as :

η = ([V₂ × I₂] ÷ [V₁ × I₁]) × 100

On rearranging we'll get :

I₂ = (η × V₁ × I₁) ÷ (V₂ × 100)

I₂ = (90 × 240 × 9) ÷ (2120 ×100)

∴ I₂ = 0.917 A