IIT JEE , AIEEE Forum - Physics , Electricity

abhijeet_0201

statement 1: a charge q is placed at the midpt of the line joining 2 equal like charges of mag Q.the system is in equilibrium irrespective of nature and mag of q

statement 2: the resultant force on q due to 2 like charges of mag Q is zero

plz tell me ur views bout it and get rates

karthik2007

I don't think it can be in equilibrium

abhijeet_0201

A-both are right,2 explains 1
B-both are right , 2 is not the reason for 1
C-1 is right,2 is wrong
D-1 is wrong ,2is right

why cant it be in equilibrium plz exp

karthik2007

See, if the charge q is positive, and the other two charges are positive, then considering the charge on the extreme left:
There is a force on it towards the right by the charge q in the middle, and there is a force again towards right by the charge Q at the left.

abhijeet_0201

okay thats waht i thought too

phyana

in the first question...............

tht is false................
this is becaz the system will be in equilibrium if and only if the charge kept at the centre of the line is small in magnitude.if u keep a big charged body in the centre then the charges at the end wil be replled/attracted by the charge at the centre thus distrurbing the equilibrium of the system...........

in second que...........

this is true always...................

if the answer is convincing plz dont forget to rate me.............

sahit.victory7

statement 1 is false statement 2 is true

Aatish

DONT BE LAZY TO READ THIS......

statement 1 is FALSE : coz equilibrium in a two charge system can be achieved only at one point that also when the charges have same sign.......NOW the equilibrium is not stable because........

let us take a simple example of two positive charges(same magnitude)......then at the mid point of the line joining them suppose we keep a test charge.....it will be in equilibrium....Now
1) if it is displaced in a direction along the line joining the two charges then a restoring force acts on it and it comes back to the null point.....

BUTTT......

2) if it displaced in perpendicular direction to the line joining the two charges then NO RESTORING FORCE acts on it and thus

THE EQUILIBRIUM IS UNSTABLE........

statement 2 is TRUE.....

bhartibhanushali

the given charge q will either be attracted or repelled equally in opposite direction
suppose both charges are +Q
if q is + then it will be repeled equally in opposite direction
if q is- then it will be attracted equally in same direction

similarly if both the charges are negative

hence it can be concluded that the nature of charges Q does have any effect on charge q

2) since no force act on charge q i.e. it can be said that two equal n opposite charge act on q th
the resultant is 0

bhartibhanushali

hence both the statement r true

Aatish

hey bharti pls see my explanation.......you may change your opinion.......

bhartibhanushali

yaa u r right. i agree with u but one thing i m not clear about

see if it is displaced in any direction then it will continue to displace
this is just due to no force act on it

how can u say that restoring force act on it {what is its source}

Aatish

See I have tried to visualize my explanation .......

By stable equilibrium i mean.....

anything in stable equilibrium will try to come back to its stable state...if displaced from that state....ok

then if you displace the charge along XY.....the electric lines of force will suggest you that it will tend to come back to its null point position........

But if it is displaced along AB then it will continue to move in that direction.........

thats why I used the term "Restoring Force".....ok.....

HOPE ITS QUITE CLEAR NOW.......

sivaramakh

syatem is not in equlilibrium

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