The -ve and +ve charge of a dipole of moment `vecP` are placed respectivley at points `-hatia` and `+hatia`. If y >> a, then the electric field intensity due to the dipole at the point located at `hatjy` is

Options

A. `a)p//2pi epsi_(0)y^(3)`
B. `b)-p//2pi epsi_(0)y^(3)`
C. c)`p//4pi epsi_(0)y^(3)`
D. d)`-p//4pi epsi_(0)y^(3)`

Answer

D

Explanation

As, electric field at any point on the equatorial line of a dipole is given by
`E_("equa") = - (1)/(4pi epsi_(0))- (p)/((r^(2) + l^(2))^(3//2))`
Given, r=y, l= a and `a lt lt y`
Hence, `E_("equa") = - (1)/(4pi epsi_(0)) (p)/((y^(2) + a^(2))^(3//2)) ~~ - (1)/(4pi epsi_(0)) (p)/(y^(3))`
Here, negative sign shows that field is anti-parallel to the dipole moment. Hence, option (d) is correct.