Question

R= 100 ohmi
U= 200V
Δt= 1h
de aflat caldura degajata Q=?

Answer 1

Presupunand ca energia electrica se transforma integral in caldura, avem 
$Q= W_{el} = \frac{U^{2}}{R} *dt= \frac{40000}{100}*3600= 1440000J=1440 kJ=1,44MJ$