# What material of a core put into the inductor would decrease the current?

Consider the $$\AC\$$ circuit: For various $$\U\$$ values set by the potentiometer, we have measured the current $$\I\$$ flowing through the circuit with and without core put inside the inductor $$\L\$$.

As a result we concluded that, without the core, the current was always bigger than with the core.

E.g.: for set $$\U = 4V\$$ the current with the core: $$\I = 4.33 \; mA\$$ and without the core $$\ I = 26.9 \; mA\$$.

The cylindrical-shaped core was made out of metal-alike material.

Questions:

• Given the fact that with the core the current was lower, what material could the core be made of? Ferromagnetic cores increase the current, right?
• What exactly does the Atr in the schematic stands for?
• Probably autotransformer. Is this homework? Are you aware of permeability? – winny Nov 16 '19 at 22:56
• Not a homework, finished my physics lab and just curious afterwards. Reading about permeability right now, thanks. – weno Nov 16 '19 at 22:57
• Good. Look up permeability and Al value. – winny Nov 16 '19 at 22:58