1. t = 3 h = 10800
W = U × I × t
W = 24V × 3 × 10800s
W = 7905600 J
7905600J ÷ 3600000J = 2,196 kWh
2. a). Rc = 3Ω + 5Ω
Rc = 8Ω
b). Rc = 3Ω + 5Ω
Rc = 1⅞Ω
3. 40 mA = 0,04A
R = U/I
R = 4,8 V/0,04 A
R = 120 Ω
4. U = P/I
U = 40 W/2,5 A
U = 16 V
5. http://img4.imageshack.us/img4/5072/obwd.png