Question

Calculate the energy stored in arranging 1C, 2C, 3C and 4C charge along with the edge of square with side 4 m?​

Answer 1

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Work done on the system is change in their potential energies in two configuration.

$q_{1} = 1\:C$

$q_{2} = 2\:C$

$q_{3} = 3\:C$

So initial potential energy of arrangement

r = 1 m .

U = h ( 2 + 6 + 3 / 1 )

$U_{initial}$ = 11h ------------ ( 1 )

Initial potential energy of arrangement

r=0.5m

$U_{final}$ = h(2+6+3/0.5)

= 22h ---------- ( 2 )

Work Done =$U_{final} - U_{initial}$

= 22h - 11h

= 11 × 9 × 10^9

= 99 × 10^9 J .