Q.

Two short dipoles (A,B), A having charges ±2 μC and length 1 cm and B having charges ±4 μC and length 1 cm are placed with their centres 80 cm apart as shown in the figure. The electric field at a point P, equi-distant from the centres of both dipoles is ______ N/C.   [2026]

1 9162×104  
2 9162×105  
3 4.52×104  
4 92×104  

Ans.

(1)

E→2=-KP2r3 ;  E→1=-2KP1r3

P1=2×10-6×10-2=2×10-8

P2=4×10-6×10-2=4×10-8

E→net=2×9×109×2×10-8(0.4)3 i^-9×109×4×10-8(0.4)3 j^

E→net=9×109×4×10-8(0.4)3(i^-j^)

|E→net|=9×104162