magnitude of Q?

If a charge q is placed at the centre of line joining two equal like charges Q,the system will be in equilibrium if q is
a)-Q2

b)-Q4

c)+Q2

d) +4Q

Plz explain yur ans ......

12 Answers

1
samagra Kr ·

You have told equilibrium and not Stable equilibrium.At the centre INTENSITY is 0.so ABCD should be the answer

1
chessenthus ·

Ok If I change the question to stable equilibrium,then what would be the answer and why?

11
Joydoot ghatak ·

i think the answer would be -Q4.

1
samagra Kr ·

only positive charge can attain stable equilibrium,(CD)
check by giving the charge Qmid a small displacement of x .
Then check which force dominates to restore it in orignal position.

49
Subhomoy Bakshi ·

stable eqm. hone se no answer possible!

11
Soham Mukherjee ·

Qq/(r2/4)+Qq/(r2/4)=-Q2/r2
=>q=-Q/8

1
chessenthus ·

huh???????????

11
Soham Mukherjee ·

it is brute force..i only guessed...

1
champ ·

Only an unlike charge can balance the system.Lets calculate the value of charge and we can guess the sign from options(since nothing given in ques)

Q q Q

Balance force on Q,because its no use of trying it on q

kQ2/x2=4KQq/x2
so,q=Q/4

hence option b)

49
Subhomoy Bakshi ·

equilibrium= all answers.
stable equilibrium= no answer.

1
chessenthus ·

I can promise you that this was the exact question( in words ) which was given to me in the test.

6
AKHIL ·

B is the correct ans....( dont take the language of the quesn too seriously!!!:P)

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