ElectrostaticsHard
Question
A charged particle of charge ′Q′ is held fixed and another charged particle of mass ′m′ and charge ′q′ (of the same sign) is released from a distance ′r′. The impulse of the force exerted by the external agent on the fixed charge by the time distance between ′Q′ and ′q′ becomes 2r is :
Options
A.

B.
C.0
D.cannot be determined
Solution
Applying conservation of energy, we get
=
+
mv2
∴
mv2 =
or v =

∴ Force required to keep Q fixed = Coulombic repulsion between the charges.
= force on charge q
∴ Impulse = change in momentum of q. = mv =
= 
∴

∴ Force required to keep Q fixed = Coulombic repulsion between the charges.
= force on charge q
∴ Impulse = change in momentum of q. = mv =
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