Questions & Answers

Question

Answers

A)5.0 A

B)3.6 A

C)2.8 A

D)2.5 A

Answer
Verified

$\eta =\dfrac{{{I}_{2}}{{V}_{2}}}{{{I}_{1}}{{V}_{1}}}=\dfrac{Powe{{r}_{out}}}{Powe{{r}_{in}}}$, where, $\eta $ is the efficiency of the transformer.

We are given that output current is 2.0 amperes and the output voltage is 440 volts. The input voltage 220 volt, and efficiency is 80 % or 0.8.

Using the formula of efficiency, we get

$\eta =\dfrac{{{I}_{out}}{{V}_{out}}}{{{I}_{in}}{{V}_{in}}}$, we want to find value of ${{I}_{in}}$

Putting the values in equation

$\begin{align}

& {{I}_{out}}=2.0A \\

& {{V}_{out}}=440V \\

& {{V}_{in}}=220V \\

& \eta =0.8 \\

\end{align}$

We get,

$0.8=\dfrac{2\times 440}{{{I}_{in}}\times 220}$

This gives us,

${{I}_{in}}=5A$

There are two types of transformers, Step-up and Step-down transformers.

Step up transformers are used for increasing low AC voltages at high currents.

Step down transformers are used for decreasing high AC voltages at low currents.

In ideal conditions, a transformer is a lossless device which perfectly transfers the electrical energy from one side to the other side.

It is a device which uses the magnetic forces. In the primary coil, the current produces the magnetic flux, this flux is transferred to the secondary coil, which follows the Lenz law to produce current from the magnetic flux.

Just like other magnetic devices, the transformer suffers from losses like Hysteresis loss and eddy loop losses.

Due to the imperfections in manufacturing, some flux will always leak out of the transformer.

A famous special type of transformer called the Tesla coil was discovered by Nikola Tesla.

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