# What is Transformer?

## What is Efficiency?

**(η)**Etta. The efficiency of any machine is always represented in percentages. The efficiency of the transformer is defined as the ratio of Electrical Output power to Electrical Input power.

For a given transformer of power factor CosƟ_{2} and
I_{2} load Current and V_{2} Transformer Terminal Voltage

Output Power of Transformer will be given as

Output Power = V_{2}
I_{2} CosƟ_{2}

Copper loss for a transformer is variable and it totally depends on load current and is given as

I_{2}^{2}R_{2} , Here R_{2}
is Total Equivalent Resistance of Transformer.

Iron loss for a given transformer is almost Constant and it
will not vary with load current. Let Iron loss for a given Transformer is P_{i}

Then Input Power for a given Transformer is

Input power = V_{2} I_{2} CosƟ_{2 }+
I_{2}^{2}R_{2} +P_{i}