Answer:
changing from a solid to a gas without changing into a liquid. :)
relation between potential difference and electric field is given as

so here we know that
d = 3 cm



So now when plates are separated to 4 cm distance carefully
the potential difference between them will change but the electric field between them will remain constant
So at distance of 4 cm also the electric field will be E = 1000 N/C
We know,
Speed = Frequency * Wavelength
Speed = 3 * 0.1 m/s [hertz = 1/sec.]
So, your final answer is 0.3 m/s
Hope this helps!!
Answer:
A.
Explanation:
All the arrows align to the point right