Question

1) if the primary coil of a transformer has 100 turns and the
secondary has 200 turns, Ns/Np = 2. Thus, a 220V input at 10A will
a) step-up to 440 V output at 5.0 A.
b) step-up to 660 V output at 5.0 A
c) step-down to 220 V output at 15.0 A
d) step-down to 110 V output at 15.0 A
ES
NS.​

Answer 1

Answer:

a) Given; Ns/Np = 2 and Ep = 220.

Since: Ns/Np = Es/Ep

=> 2 = Es/220

=>  Es = 440V.

Now,

  Ip = 10A

Since, Ip/Is=Ns/Np

Ip/Is = 2

=> 10/Is = 2

Is = 5A.

Answer 2

Given :

Number of turns in primary coil of a transformer (N₁)= 100

Number of turns in the secondary coil of a transformer (N₂) = 200

Voltage in the primary (V₁) = 220 V

Current in the primary (I₁)= 10 A

To find :

1. Secondary Voltage (V₂)
2. Current in the secondary coil (I₂)

Explanation :

• A step up transformer is the one in which voltage in the secondary is greater than that in the primary.
• Similarly A step down transformer is the one in which the voltage drops from primary to the secondary coil.
• The most basic theorem for relation between primary and secondary coils is,                  $N_{1} V_{1} I_{1} = N_{2} V_{2} I_{2}$  ; or

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

Solution :

Step 1,

Substituting the given values in the equation, we get,

                            $\frac{N_{1} }{N_{2} } = \frac{V_{1} }{V_{2} } ;$    $\frac{100}{200}= \frac{220}{V_{2} }$

Therefore,              $V_{2} = 440 V$

Step 2,

For $I_{2}$, substituting the values we get,

                           $\frac{N_{1} }{N_{2} } = \frac{I_{2} }{I_{1} } ; \frac{100}{200} = \frac{I_{2} }{10 }$

      therefore,        $I_{2} = 5A$

• Since, the voltage in the secondary coil is greater than that in the primary . The transformer is A Step up Transformer .

Final answer :

Hence, the correct statement is option (A) step up to 440V output at 5.0 A.