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Q1) A particle of mass m and charge q is placed at rest in a uniform electric field E and then released.
The kinetic energy attend by the particle after moving a distance y is [AFMC 1997]
Initially charged particle was at rest Initial kinetic energy Ki=0
After releasing charge particle , it attends velocity Final Kinetic=Kf > 0
Therefore kinetic energy is changed Now According to work energy theorem ∆K=W
Therefore Kf – Ki=Force x displacement
Ki – 0=F x y displacement is y given =Eqy ( Force on the charge in electric field E=Eq
Answer is (b)