[单选题]
Two parallel plates ar
luk 6l/d kk vm4l6qw2t ::lem6e separated by a distance d and connec
gn:n 6,:s+ s +uruntnela94g hted to a battery of potential difference V as shown in the diagram. A proton released from the positive pla
ang+gn+4 ,hsrls 96 :nnteu:ute gains a speed v when it reaches the opposite plate.
The separation of the plates is decreased to $\frac{d}{2}$.
What would be the speed gained by an alpha particle released from the positive plate, when it reaches the opposite plate?
