Answer:
The answer to your question is the letter D. 2.5 N
Explanation:
The electrostatic force is the same in both directions,
If the electrostatic force on B due to A is 2.5 N, the magnitude of the electrostatic force on A due to B must be 2.5N.
Maybe the direction is different but the magnitude is the same.
Answer:
The potential difference between the plates is 
Explanation:
Given that,
Distance = 1.4 mm
Electric field strength 
Let the potential difference is V.
We need to calculate the potential difference between the plates
Using formula of electric field


Where, V = potential
d = distance
Put the value into the formula


Hence, The potential difference between the plates is 
A. Energy is transmitted by all waves.
Formula for potential energy is V=mgh, where m is mass in KG, g is earth acceleration (10 m/s^2), and h its height in meters. We know mass, acceleration is constant and also known, we know height also. Lets substitute
V=75*10*300=225000[J]=225[kJ] - its the answer