An infinte wire having linear charge density `lambda` is arranged as shown in fig. A charge particle of mass m and charge q is released charged q is released from point P. Find the initial acceleration of the particle just after the particle is released.

Answer

`-(lambda)/(2 pi epsilon_(0)R)(-hat j)`.

Explanation

Electric field due to straight wires will cancel out. The net electric field will be due to semicircular wire only. Hence,
`vecE_("net")=vecE_("circular")=(lambda)/(2 pi epsilon_(0)R)(-hat j)`
so, acceleration is
` vec(a) = (q vecE_("net"))/(m)=(q lambda)/(2 pi epsilon_(0)mR)(hat j)`.