Equillibrium

Four equal charges q0 are kept fixed on the vertices of a square of side 'a'. A charge q is kept at the center of the square.

Then :
a) charge q is in stable equilibrium
b) charge q is not in stable equilibrium
c) charge q is in stable equilibrium if qq0 <0
d) charge q is in stable equilibrium if qq0 >0

:(

13 Answers

1357
Manish Shankar ·

I think its (d)

33
Abhishek Priyam ·

:)

same pinch...

But the answer given is (b) so i want some explanation :-|

1
greatvishal swami ·

1. if charges are opp. displace q horizontly it will not return to orig pos

2. if charges hav same charge displace q vertically

1
greatvishal swami ·

so ans shld be b

1
Akand ·

k ill tel wat vishal means...............
consider the square as a plane in 2d.........so if d charge q is moved inside d plane itll get restored automaticaly and is in eql...
but if u move it out horizontally, itll be repelled by d charges once it moves out of d plane and is thrown out completely..........
so it is unstable eql.... if u consider 3D

1
greatvishal swami ·

bt 1 has to always consider it in 3D

1
skygirl ·

probable explanation:-

1
skygirl ·

1
skygirl ·

this explanation is for matching the ans...
at first look my reaction was 'd' only... i still dunno y it should not be d
:P

33
Abhishek Priyam ·

Got it !!

Thnx

1
skygirl ·

btw, wat did u get ?
are u convinced ?
........i am not :P
had it been a question in some exam, i would have ticked 'd' only... :P

1
skygirl ·

well my doubt is, though d2<d1, but there are also components of the other two forces in opp direction... that will atleast 'try' to bring that charge q to equilibrium ...

1
skygirl ·

ok doubt clear...

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