Does a Step-Up Transformer Really Increase Light Bulb Brightness?

[steve oliver]

theroteically using transformers can't create power then why a light bulb connected with a step up transformer can become brighter

 

[derek10]

Useful links you should check if you didn't:

Voltage: https://en.wikipedia.org/wiki/Voltage
Ohm's law: https://en.wikipedia.org/wiki/Ohm's_law
Current: https://en.wikipedia.org/wiki/Electric_current
Transformer: https://en.wikipedia.org/wiki/Transformer
Power: V x I, I²R, V²/R

A step up transformer doesn't generate any extra power, it only interchanges current with voltage: it can elevate the voltage but the maximum current provided by its output lowers wrt to input current and provides he same (or lower, due to efficiency issues) power.
Because a bulb requires a voltage that the transformer's output provides to generate enough current to light up its filament (or LED or whatever), but if the transformer can't provide enough current , the bulb won't light up.

 

[CWatters]

There are two ways to visualise a power supply and a load (light bulb).

1) The power supply delivers a certain amount of power to the load.
2) The load draws (sucks?) a certain amount of power from the supply.

It's sometimes better to think in terms of 2) rather than 1).

 

[steve oliver]

then what makes the bulb connected to a step up transformer become brighter

 

[Dale]

The bulb is brighter due to Increased power output from the source. The transformer does not provide any power itself, but it can make a load draw more power from a source.