Question

E=32 ohmi
U=30V
P=6W
r=?
R=?
t=?;q=720C

Answer 1

q=I*t=>t=q/I
P=UI=>I=P/U=6/30=0,2 A
t=q/I=t=q/I/0,2=3600 s=1 h
R=U/I=30/0,2=150 Ω
I=E/(R+r)<=>IR+Ir=E=>r=(E-IR)/I=(32-30)/0,2=2/0,2=10 Ω

Answer 2

P=U•I=>6 = 30•I => I=0.2A
P=I•I•R=0,04•R=>R=150 ohm

I=q/t> t=q/I=3600 s=1 ora

I=E/(R+r) => 0.2=32/(150+r)

30+0.2r=32 => r=(32-30)/0.2=10 ohm

Asta in cazul in care P este puterea rezistorului, nu ai specificat