Practice question

**Heating effect** depends on I² R t, explaining why high currents cause significant heating, need for thick wires, fuses. Energy supplied by battery ε I t = I²(R+r)t, split between external and internal as per resistances. Total resistance: Rtₒtₐl = 10 + 2 = 12 Ω . Current: I = (ε/Rtₒtₐl) = (12/12) = 1 A . Power: P = I² r = 1² × 2 = 2 W . Applying I = n e A v_d, R = ρ l/A, R_t = R₀[1+αΔT], Kirchhoff's ΣI=0, ΣV=0, R_eq series/parallel, V = ε - I r and P = I²R, evaluation yields 2.0 W,