Q.

Suppose a uniformly charged wall provides a uniform electric field of 2×104 N/C normally. A charged particle of mass 2g being suspended through a silk thread of length 20 cm and remains stayed at a distance of 10 cm from the wall. Then the charge on the particle will be 1xμC where x= __________. [use g = 10 m/s2]     [2024]


Ans.

(3)

sinθ=1020=12θ=30°

Along x-axis 

(fnet)y=0  (for equilibrium)

Tsinθ=qE            ...(i)

Along y-axis

(fnet)x=0  (for equilibrium)

Tcosθ=mg            ...(ii)

From (i) divide by (ii), tanθ=qEmg

q=mgtanθE

=2×10-3×102×104×13=10-63C

q=13μCx=3