Why transformer is a passive circuit?

Can anyone help me out in explaining why transformers are considered as passive circuits. Transformers performs by stepping up/down voltage/current,changes low input power to high output and vice versa.

But these are the basic definitions of an active device.A transistor also does this.Then why is transformer called a passive device?

Updated Answer-

A transformer is considered a passive device because it does not generate energy by itself or add any new energy into the circuit. Instead, it merely transforms the existing electrical energy from one voltage level to another.

The active and passive designations for electrical components do not have anything to do with the function or the amount of power they can handle, but rather the ability to introduce net energy into the system.

Active devices, such as transistors, can amplify the signals they receive because they have an external power source that allows them to output more power than they receive.

They introduce new energy into the system and can generate a larger output signal than the input signal. They can also perform other functions like oscillation, signal detection, or modulation, among others.

On the other hand, passive devices, such as resistors, capacitors, inductors, and transformers, cannot generate energy by themselves or increase the power of a signal.

They can only change the existing energy from one form to another or store it and release it later. In the case of transformers, they can step-up or step-down the voltage level of an alternating current (AC) signal, but the output power (considering ideal conditions) remains equal to the input power. They can't output more power than they take in.

So, even though transformers can increase or decrease the voltage or current, they're passive because they are not adding any extra energy to the system.

They are simply transforming the form of the existing energy without any amplification.