how acidity can be determine in alcohols

resonance or inductive effect of attached groups

an alkyl group is a weak electron donor, increasing electron density on whatever it is attached to. An increase in electron density leads to a strenthening of neighbouring bonds. Disregarding any other possible influences, the O-H bond of an alcohol becomes stronger, and thus less acidic, when electron density is increased. This explains why methanol is more acidic than ethanol, and why tert-butanol is a very weak acid for an alcohol (and thus makes a strong base).

In terms of polarity, an increase of electronic charge to be shared between two atoms will decrease the polarity. In other words, as polarity is the separation of electric charge between two atoms, anything that adds more electronic density to the bond and thus decreases polarity will increase bond strength.