Explain the term : 'Heating effect of electric current'

Question

(i) Explain the term : 'Heating effect of electric current'.
(ii) Derive an expression for the heat produced by electric current and state Joule's Law.
(iii) Explain why an inert gas like argon is filled in bulbs

Answer 1

(i) Heating effect of electric current : When an electric current is passed through a high resistance wire like nichrome, the resistance wire becomes very hot and produces heat. This is called heating effect of electric current. 
(ii) P = V ×Q/T
    P = VI
    E = P × t
      = VI × t = VIt
   E = IRIt [V = IR; Ohm's law]
      = I²Rt. 
Joule's law : When current of I ampere flows in a wire resistance RΩ for t seconds, the heat
energy dissipated by it is given by H = I²Rt.
(iii) The bulbs are usually filled with chemically inactive nitrogen and argon gas so that filament does not burn out and the life of filament is prolonged