Answer:
10 m/s
Explanation:
Velocity = frequency * wavelength
Velocity = 2.5 * 4
Velocity = 10 m/s
Explanation:
The given data is as follows.
Area (A) = 0.7
.
Electric field between the plates, (E) = 55 N/C
Since, electric field is related to surface charge density as follows.

Also, E = 
or, 
Therefore, charge will be calculated as follows.
Q = 
= 
=
= 341 pC
Thus, we can conclude that magnitude of the charge on each plate is 341 pC.
D.3. a.4. sorry this is all i know hope this helps