Question

. A large solid sphere with uniformly distributed
positive charge has a smooth narrow tunnel
through its centre. A small particle with
negative charge, initially at rest far from the
sphere, approaches it along the line of the
tunnel, reaches its surface with a speed v,
and passes through the tunnel. Its speed at
the centre of the sphere will be
A. O
B. -V
C. Dar
D. V1.50
​

Answer 1

let the charge on particle be q . mass m and that on the sphere be Q .

the energy of particle at infinite seperation is zero as u=0 and k =0.

but when it reaches the center it will have got accelerated by the gravitational force and have gained a velocity (v).

so the total energy here now= U +ke

= (kqQ/2R)[3-R-2] + mv2/2 = 0 .

so by solving that equ we will get the ans as (d)option.

so d option is correct.

mark it as brainlist ans ...