How aware is a character of the damage their spells/attacks deal?

Say a character casts two Fireballs at CL 10. The character aims at a field intentionally and hits nothing. Normally That’d be 10d6 damage. But in this scenario the first deals minimum damage (10) and the second deals maximum damage (60). Would the character be able to understand which is stronger or if there were any differences in damage? If so, to what extent? Would they be able to tell the dealt an exact number damage?

In the second scenario, the character deals gets two hits with their longsword (1d8+1 damage). Say the first crits, but they get a horrible roll and only deal 3 damage. The second does not crit but deals maximum damage (9). Would the character know they got a crit? If so, would they understand that the critical dealt less damage than their normal attack?

If we determine that characters know the number damage they deal, would they also be aware when something resisted that damage and a hit of 9 damage only translates into 4 Hit points lost (because of DR 5/-)?

This is mostly for a roleplay stance, I want to know if my characters would understand that the monster they’re fighting might not be super scary, they just rolled low to damage them. Or that the enemy resists their attacks, but factoring in the numbers they understand they still have a chance to damage them.

Edit

I’m not looking to see if a character know’s how much HP their opponent has lost. But rather, if the character knows how hard they hit or how strong the blow they are swinging is supposed to be.