How do you know which way electrons flow in a Voltaic Cell?

Electric current flows from the positive terminal to the negative terminal outside of a Voltaic Cell. The flow of electrons is in the opposite direction of electric current since electron carries negative charge.

A voltmeter or multimeter can be used to check the voltage across the terminals of the Voltaic Cell.

connect a voltmeter. The electrons flow out of the negative terminal and into the other one.

.