What creates voltage level in a lemon battery? Measuring with a multimeter?
They only have a weak effect on the voltage. The voltage will go with the logarithm of the “acidity”. You can look up “pH” and how “pH meters” work. The voltage will depend very strongly on the types of metals you use for electrodes, though. If you want to measure acidity, you are going to do better with pH-paper than with an electrochemical measurement. It is easier and slightly more precise. Even better would be a “titration”. That’s a procedure real chemists use a lot when they neutralize an acid with a base of known concentration. You can do, too. It is neither a hard nor a dangerous experiment if you are careful and get some help with the basics. Essentially you drip a base solution into your test solution and watch the pH with a very sensitive indicator die. The solution with the acid and the die will change color as soon as all acid has been neutralized by your base. You measure the volume of your base needed to achieve neutralization and that is a very good measurement of acid
