A plate A of a parallel plate capacitor is fixed, while the plate B is attached to the wall by a spring and can move remaining parallel to the plate A (see figure). The capacitor is charged, plate B starts moving and comes to rest in an equilibrium position. The separation between the plates d decreases by 10%. What will be the decrease in the plate separation if the charging is done in a very short time that the plate B could not shift noticeably.
1) 10% 2) 8.1% 3) 9% 4) 6.3%