Oblicz opór żarówki o mocy 60 V ieżeli jest ona zasilana prądem 230V

P=60W U=230V R=? --------------------------------------------------------- P=U*I I=U/R P=U²/R R=U²/P=230²/60=882Ω [V²/W=V²/(V*A)=V/A=Ω]

P = 60 W  ( wat) U = 230 V ( wolt) ------------------------ R = ? Mamy P = U*I  =>  i = P / U = 60 W / 230 v =  6/23 A oraz R = U/ I = 230 V / ( 6/23) A = 230*(23/6) om = 882 om ==================================================