The acceleration of projected change in y-direction is, ay=−
F
m
ay=−
qE
m
Substitute the given values in the above equation. ay=−
(1×10−6)(1×103)
2×10−3
ay=−
1
2
m∕s2 The vertical component of the projection velocity is, uy=u‌sin‌45° If the particle is not to hit upper plate, then (uy)2≤2ay(y) (u‌sin‌45°)2≤2×