1I THINK IT IS B ONLY!!
an electric dipole is kept on the axis of a uniformly charged ring at distance of r/√2 frm the centre of the ring .the direction of dipole moment is along the axis dipole moment is p charge of ring is q n radius is r force on dipole is nearly
(A)4kpq/3√3r2
(b)4kpq/3√3r3
(c)2kpq/3√3r3
(d)zero
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21 Answers
11just one thing 'K' isnt mentioned in the problem
so you cant confirm dimensions (the answer too)
1bhaiya are u sure the ans is c only even me got this but is nearly ve anything to do wid it . ans given is d
62no mani it is not cancelled..
think that it is a vector and the horzontal component is in opposite direction!
11i would like to say
electric dipole is a vector
if that charge is placed at the center of the ring then it is bound to be zero as all yhe vectors cancel themselves
but if it is at a height of R then abhishek is correct
11http://targetiit.com/profile/1412.html
my name is Subash
not shubhas...
33May be...
" force on dipole is nearly ..."
But it can't be exactly zero...
Lets see what are other's opinion...
33:D good point subhas...
thats 1/4πε0
thats a stupid convention of some books...
but it is mentioned in good books and exams...
[3]
1@priyam me too got the same ans bt ans given is d r we missing sumthing?
33Force between two charge varies as 1/r2
between one charge and one dipole as 1/r3
between two dipoles as 1/r4
33It can't be zero... :O
it got to be (B).. to be exact for the point dipole..
33E at r/√2 =2Kq
3√3r2 ..(here say -q' is placed..)
Now at a dist dr from r/√2
change in E=dE=4kqdr/(3√3r3)
Now force on -q'=-E
on +q' =E+dE
net force on dipole =dEa
=4kq(q'dr)/(3√3r3)
q'dr=p
so 4kq(p)/(3√3r3) ..ans..
33Phew... i got
(some constant)pq/3√3r3
well bana kar dekhna padega constant kya hai.... will do this when i will bring my copy... :)