Electric Charge and Electric Force - AP Physics 2

1. What is the direction of the electric field due to a positive charge?

   Radially outward from the charge. Field lines point away from positive charges.

2. Identify the SI unit for electric field strength.

   Newton per Coulomb (N/C). Also equivalent to V/m (volts per meter).

3. What is the electric field on the surface of a charged conductor?

   Perpendicular to the surface. Field is normal to equipotential surfaces.

4. What is the effect of a charged insulator on a nearby uncharged conductor?

   Induces a charge separation. Creates surface charges that cancel internal field.

5. Find the force on a charge in a uniform electric field.

   $F = qE$. Force equals charge times field strength.

6. What is the charge of an electron?

   $-1.6 \times 10^{-19} \text{ C}$. Fundamental negative charge magnitude.

7. What is the principle of superposition for electric forces?

   Net force is vector sum of individual forces. Forces add vectorially from all charges.

8. What is the electric potential at a point due to a point charge?

   $V = k \frac{q}{r}$. Potential decreases with distance from positive charge.

9. State the formula for electric force between two charges.

   $F = k \frac{|q_1 q_2|}{r^2}$. Coulomb's Law for electrostatic force.

10. Determine the potential difference between two points in an electric field.

    $\triangle V = Ed$. For uniform field, voltage change is field times distance.

11. Calculate the force between two $1 \text{ C}$ charges $1 \text{ m}$ apart.

    $F = 8.99 \times 10^9 \text{ N}$. Using $F = k\frac{|q_1 q_2|}{r^2}$ with given values.

12. Determine the electric force on a $5 \text{ C}$ charge in a $10 \text{ N/C}$ field.

    $F = 50 \text{ N}$. Using $F = qE$ with given charge and field.

13. State Coulomb's Law.

    $F = k \frac{|q_1 q_2|}{r^2}$. Force between charges is proportional to product of charges, inversely proportional to distance squared.

14. State Gauss's Law.

    $\text{Flux} = \frac{Q_{\text{enc}}}{\varepsilon_0}$. Electric flux through closed surface equals enclosed charge over $\varepsilon_0$.

15. Calculate the electric potential at $2 \text{ m}$ from a $3 \text{ C}$ charge.

    $V = 1.35 \times 10^{10} \text{ V}$. Using $V = k\frac{q}{r}$ with given values.

16. What is meant by a conservative electric field?

    Work done is path independent. Electric fields are conservative force fields.

17. What is the relationship between electric field and voltage?

    $E = -\frac{dV}{dx}$. Field points from high to low potential.

18. Calculate the work done moving a $1 \text{ C}$ charge across $10 \text{ V}$.

    $W = 10 \text{ J}$. Work equals charge times potential difference.

19. Define electric field.

    Force per unit charge, $E = \frac{F}{q}$. Electric force per unit test charge.

20. What is the charge of a proton?

    +1.$6 \times 10^{-19} \text{ C}$. Fundamental positive charge magnitude.

21. What is the formula for electric potential energy?

    $U = k \frac{q_1 q_2}{r}$. Energy increases when like charges approach.

22. What is the formula for the potential energy of a dipole in an electric field?

    $U = -pE \text{cos}(\theta)$. Energy depends on dipole orientation relative to field.

23. State the formula for electric potential (voltage).

    $V = \frac{U}{q}$. Electric potential energy per unit charge.

24. What is the magnitude of the electric field in a parallel plate capacitor?

    $E = \frac{\text{V}}{d}$. Uniform field between parallel plates.

25. What is the formula for electric field due to a point charge?

    $E = k \frac{|q|}{r^2}$. Field strength decreases with distance squared.

26. What is the net charge inside a conductor in electrostatic equilibrium?

    Zero inside the conductor. All excess charge resides on surface.

27. State the formula for the torque on a dipole in a uniform electric field.

    $\tau = pE \text{sin}(\theta)$. Maximum torque when dipole perpendicular to field.

28. What is the value of the Coulomb constant, $k$?

    $8.99 \times 10^9 \text{ N m}^2/\text{C}^2$. Also written as $\frac{1}{4\pi\varepsilon_0}$.

29. Identify the formula for the work done by an electric force.

    $W = qEd$. Work equals force times distance moved.

30. Calculate the potential energy of a $2 \text{ C}$ charge at $5 \text{ V}$.

    $U = 10 \text{ J}$. Using $U = qV$ with given charge and potential.

31. What is the electric field inside a conductor in electrostatic equilibrium?

    Zero. Charges redistribute to cancel internal field.

32. What are the units of electric potential (voltage)?

    Volt (V). One volt equals one joule per coulomb.

33. What is the permittivity of free space, $\text{ε}_0$?

    $8.85 \times 10^{-12} \text{ C}^2/\text{N m}^2$. Fundamental constant in electromagnetism.

34. What is the direction of the electric field due to a negative charge?

    Radially inward toward the charge. Field lines point toward negative charges.

35. State the relationship between potential energy and work done by electric forces.

    $U_i - U_f = W_{\text{done}}$. Conservation of energy in electric fields.

36. Identify the relationship between electric field and force on a charged particle.

    $F = qE$. Definition of electric field strength.

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