User:Inconspicuum/Physics (A Level)/Electric Fields Questions

Electric Force

e = 1.6 x 10^-19C

1. A positron (charge +e) is 1 μm from a lithium nucleus (charge +3e). What is the magnitude of the force acting on each of the particles? In what direction is it acting?
2. An electron is 1mm from the positively charged plate in a uniform electric field. The potential difference between the plates is 20V, and the plates are 10cm apart. What force is acting on the electron? In what direction?
3. The acceleration due to gravity around a point mass is constant, irrespective of the mass of the objects it is acting on. The acceleration due to electricity around a point charge is not. Use Newton's Second Law (F=ma) to explain this.
4. An insulator contains charged particles, even though the overall charge on the insulator is 0. Why is the insulator attracted by a nearby charge?
5. Where in the charged conducting plates which create a uniform electric field would you expect to find the charge located? Why?

Electric Field

1. Two metal plates are connected to a 9V battery with negligible internal resistance. If the plates are 10cm apart, what is the electric field at either of the plates?
2. What is the electric field at the midpoint between the plates?
3. The charge on an electron is -1.6 x 10^-19 C. What is the electric field 1μm from a hydrogen nucleus?
4. What is the direction of this field?
5. A 2C charge is placed 1m from a -1C charge. At what point will the electric field be 0?

Electric Potential

ε₀ = 8.85 x 10^-12 Fm^-1

1. Draw a diagram of a uniform electric field between two plates, showing the field lines and the equipotentials.
2. Do the same for the electric field around a point charge.
3. The potential difference between two plates is 100V. What is the potential difference between a point halfway between the plates and one of the plates?
4. What is the electric potential at a point 0.2m from an alpha particle (charge on an electron = -1.6 x 10^-19C)?
5. What is the electric potential energy of an electron at the negative electrode of an electron gun if the potential difference between the electrodes is 10V?

Electric Potential Energy

k = 8.99 x 10⁹ Nm²C^-2

1. Convert 5 x 10^-13 J to MeV.
2. Convert 0.9 GeV to J.
3. What is the potential energy of an electron at the negatively charged plate of a uniform electric field when the potential difference between the two plates is 100V?
4. What is the potential energy of a 2C charge 2cm from a 0.5C charge?
5. What is represented by the gradient of a graph of electric potential energy against distance from some charge?