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