Could someone please explain all the questions in pictures?

4. [-/2 Points] DETAILS OSUNIPHYS1 24.3.WA.019. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER (a) What is the potential difference VA - Vg between two points A and B situated at 28.0 cm and 56.0 cm respectively from a 6.90 JC point charge? (b) Where should point B be moved to in order to increase this potential difference by a factor of two? 14.0 cm from the point charge o an infinite distance from the point charge 112.0 cm from the point charge 42.0 cm from the point charge 84.0 cm from the point charge Additional Materials Reading 5. [-/2 Points] DETAILS OSUNIPHYS1 24.6.P.070. MY NOTES ASK YOUR TEACHER PRACTICE ANOTHER A simple and common technique for accelerating electrons is shown in the figure below, where there is a uniform electric field between two plates. Electrons are released, usually from a hot filament, near the negative plate, and there is a small hole in the positive plate that allows the electrons to continue moving. (a) Calculate the acceleration (in m/s") of the electron if the field strength is 1.60 x 10" N/C. (Enter the magnitude.) m/s2 (b) Explain why the electron will not be pulled back to the positive plate once it moves through the hole. The other side of the positive plate also has a negative charge. The force of gravity is too strong. There is no field outside the plates. Additional Materials Reading