Question

Derive an expression for electric energy consumed in a device in terms of V,I and t, where V is the potential difference applied to it, I is the current drawn by it and t is the time for which current flows ?

Answer 1

We know that work done = W = QV

P =W/t
Now, P =QV/t
         V = IR 
         P =Q/t*IR =I²R
    Energy = P × t
               = I²R × t
              =V²/R²*R*t=V²/R *t

Energy = V²/R
Where V = voltage, R = resistance, t = time