battery performance

I just bought a new Samsung Note 9 (Exynos 9810). Little did I know that the model I ordered was the EU version and not the US version, so the charger I received was unusable with any of my power sockets. I ordered an adapter online but thanks to my impatience, decided to just charge the new...

Hi everyone. I am curious, as a general rule, how much does lowering the screen brightness on a laptop affect its battery life? Like, how much longer battery life can one expect in general when running a laptop's screen brightness at 100% vs 75% vs 50% vs 25% vs 0%? Thank you.