An -particle (charge

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

\alpha

-particle (charge

+2e

, mass

6.64\times10^{-27}\,\text{kg}

) is fired toward a positively charged metal plate that is 120 kV higher in electric potential than the launch point. What minimum speed must the

\alpha

-particle have at launch if it is to reach the plate and momentarily come to rest there? (a)

2.4\times10^{6}\,\text{m/s}

(b)

1.5\times10^{6}\,\text{m/s}

(c)

3.4\times10^{6}\,\text{m/s}

(d)

4.8\times10^{6}\,\text{m/s}