At the corners of an equilateral triangle of side a (1 metre), three point charges are placed (each of 0.1 C ). If this system is supplied energy at the rate of 1 kw , then calculate the time required to move one of the mid-point of the line joining the other two.

Step-by-step solution

Initial potential energy of the system array l = 1 4 ₀ [ q ² a + q ² a + q ² a ]= 1 4 ₀ ( 3 q ² a ) =9 10⁹ (3 (0.1)² 1 )=27 10⁷ ~J array Let charge at A is moved to mid-point O Then final potential energy of thhe system aligned U _ f &= 1 4 ₀ [ 2 q ² ( a / 2) + q ² a ] &=5 1 4 ₀ ( q ² a ² )=45 10⁷ ~J aligned Work done = U _ f - U _ i =18 10⁷ ~J Also, energy supplied per sec =1000 ~J (given) Time required to move one of the mid-point of the line joining the other two t = 18 10⁷ 1000 =18 10⁴ ~s =50 ~h