Conservation of Electric Charge and Charging - AP Physics 2

1. What is the relationship between electric field and force?

   $E = \frac{F}{q}$. Electric field is force per unit charge.

2. Describe the charge distribution in a charged conductor at equilibrium.

   Charge resides on the surface. Electric field inside conductor is zero in equilibrium.

3. What is an insulator?

   A material that resists the movement of electric charge. Electrons are tightly bound and cannot move freely.

4. What is the principle of charge quantization?

   Charge exists in discrete packets, multiples of $e$. Charge comes in integer multiples of elementary charge.

5. Describe the direction of electric field lines towards a negative charge.

   Inward. Negative charges create inward-pointing field lines.

6. State the unit of electric charge in the International System.

   Coulomb (C). Named after Charles-Augustin de Coulomb.

7. Identify the process that results in a charged object without contact.

   Charging by induction. Charges separate due to electric field influence without touching.

8. What is the net charge of an atom?

   Zero. Equal numbers of protons and electrons cancel out.

9. What is the primary principle behind the operation of a Van de Graaff generator?

   Charge transfer by contact. Continuously transfers charge through moving belt mechanism.

10. Find the net charge of an object with 5 excess electrons.

    -8.$0 \times 10^{-19} \text{ C}$. Multiply 5 electrons by $-1.6 \times 10^{-19}$ C each.

11. State the formula for electric potential energy.

    $U = k \frac{q_1 q_2}{r}$. Energy required to bring charges from infinity to distance $r$.

12. Identify the process that results in a charged object by contact.

    Charging by conduction. Direct transfer of electrons through physical contact.

13. Define a polarized object.

    An object with separated positive and negative charges. Electric field causes charge separation within the object.

14. What is the primary factor affecting the force between two point charges?

    Distance between the charges. Distance appears squared in denominator of Coulomb's law.

15. What is the value of the elementary charge $e$?

    1.$6 \times 10^{-19} \text{ C}$. The fundamental unit of electric charge in nature.

16. What happens to the net charge during charging by conduction?

    Net charge is transferred between objects. Electrons move from one object to another through contact.

17. What is the effect of charge quantization on macroscopic scales?

    Negligible, charge appears continuous. Discrete nature becomes insignificant at large scales.

18. What is the charge of a proton?

    +1.$6 \times 10^{-19} \text{ C}$. Equal in magnitude to elementary charge but positive.

19. What is a triboelectric series?

    A list ranking materials based on their tendency to gain or lose electrons. Predicts which materials gain or lose electrons when rubbed.

20. What is the net charge on an isolated system after any internal charge redistribution?

    Remains constant. Conservation of charge applies to all closed systems.

21. What is meant by conservation of electric charge?

    Total electric charge in an isolated system remains constant. A fundamental law stating charge cannot be created or destroyed.

22. What is the symbol for electric charge?

    Q. Standard symbol used in physics equations and formulas.

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

    Zero. Free charges redistribute to cancel internal fields.

24. Describe the direction of electric field lines from a positive charge.

    Outward. Positive charges create outward-pointing field lines.

25. What is an electric field line?

    A line that represents the direction of the electric field. Shows direction and relative strength of electric field.

26. What is the charge of an electron?

    -1.$6 \times 10^{-19} \text{ C}$. Equal in magnitude to elementary charge but negative.

27. What is the effect of increasing the distance between two charges on the force?

    Force decreases. Force follows inverse square law with distance.

28. What is a grounding process?

    Process of neutralizing charge by connecting to Earth. Earth acts as an infinite charge reservoir.

29. What happens to the net charge during charging by induction?

    Net charge redistributes within the object. Charges separate but total charge remains unchanged.

30. What is meant by an electrically neutral object?

    An object with equal numbers of protons and electrons. Net charge is zero due to equal positive and negative charges.

31. State Coulomb's Law.

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

32. What is a conductor?

    A material that allows free movement of electric charge. Contains mobile charge carriers like free electrons.

33. What is a Coulomb?

    The quantity of charge transported by 1 ampere in 1 second. Defines the unit based on electric current and time.

34. Define induced charge.

    Charge redistribution in response to a nearby charge. External electric field causes internal charge separation.

35. Determine the force if the charge is doubled while distance remains constant.

    Force doubles. Force is directly proportional to charge magnitude.

36. What is the effect of a charged object on a neutral insulator?

    Induces polarization. Electric field aligns dipoles in the insulating material.

37. What is the result of bringing a charged rod near a neutral metal sphere?

    The sphere becomes polarized. Electric field induces charge separation without contact.

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