Conservation of Electric Charge - AP Physics C Electricity and Magnetism

1. What is the formula for electric charge ($q$) in terms of current ($I$) and time ($t$)?

   $q = I \times t$. Charge equals current multiplied by time.

2. Determine the charge of a system initially neutral after losing 2 electrons.

   Positive. Losing electrons creates positive charge.

3. Identify the charge of an object gaining electrons through induction.

   Negative. Induction attracts electrons to the object.

4. Calculate the total charge transferred by a 3 A current for 2 seconds.

   6 C. Using $q = It$: $q = 3 \times 2 = 6$ C.

5. Identify the SI unit of electric charge.

   Coulomb (C). Standard unit for measuring electric charge.

6. Calculate the charge transferred by a 4 A current in 3 seconds.

   12 C. Using $q = It$: $q = 4 \times 3 = 12$ C.

7. Identify the charge on an object after losing 3 electrons.

   Positive. Losing electrons leaves positive charge.

8. What is the net charge of an atom with 3 protons and 3 electrons?

   Neutral. Equal protons and electrons balance charge.

9. Identify the charge state of an object with an excess of 10 electrons.

   Negative. Extra electrons create negative charge.

10. Identify the result of charging by friction between a rubber rod and fur.

    Rubber rod becomes negative. Rubber attracts electrons from fur.

11. Find the total charge if $q_1 = 2C$ and $q_2 = -2C$ are combined.

    0 C. Equal and opposite charges sum to zero.

12. What is the charge of a molecule with 5 protons and 4 electrons?

    Positive. More protons than electrons creates positive ion.

13. State the fundamental charge of a proton.

    $+1.6 \times 10^{-19}$ Coulombs. Elementary charge with positive sign.

14. What is the charge of an atom with 6 protons and 7 electrons?

    Negative. More electrons than protons creates negative charge.

15. What is the net charge of a system with $+5C$ and $-5C$ charges?

    0 C. Equal magnitude charges cancel to zero.

16. What is the charge of an ion with 9 protons and 8 electrons?

    Positive. One more proton than electron creates positive charge.

17. What is the charge of a body that has lost electrons?

    Positive. Electron deficiency creates positive charge.

18. Identify the charge on a body losing electrons during contact charging.

    Positive. Contact transfers electrons away from body.

19. Which process involves charging without direct contact?

    Induction. Charge redistribution without physical contact.

20. Calculate the total charge for 0.5 A current flowing for 10 seconds.

    5 C. Using $q = It$: $q = 0.5 \times 10 = 5$ C.

21. What happens to the total charge when two objects are charged by friction?

    Total charge is conserved. Equal and opposite charges are created simultaneously.

22. Which law states that like charges repel and opposite charges attract?

    Coulomb's Law. Force law governing charged particle interactions.

23. What is the charge state of an object after gaining 5 electrons?

    Negative. Gaining electrons creates negative charge.

24. What is the charge of a body that has gained electrons?

    Negative. Excess electrons create negative charge.

25. Find the charge when a 1.5 A current flows for 4 seconds.

    6 C. Using $q = It$: $q = 1.5 \times 4 = 6$ C.

26. What is the principle of conservation of electric charge?

    Total electric charge in an isolated system is constant. Charge cannot be created or destroyed, only transferred.

27. Calculate the charge transferred by a 2 A current in 5 seconds.

    10 C. Using $q = It$: $q = 2 \times 5 = 10$ C.

28. State the fundamental charge of an electron.

    $-1.6 \times 10^{-19}$ Coulombs. Elementary charge with negative sign.

29. Find the total charge if $q_1 = 3C$ and $q_2 = -3C$ are combined.

    0 C. Equal and opposite charges cancel completely.

30. Identify the charge on an atom with an equal number of protons and electrons.

    Neutral. Equal numbers of positive and negative charges cancel.

31. Which process involves charging an object by direct contact?

    Conduction. Direct physical contact transfers charge.

32. What do you call an atom that has lost or gained electrons?

    Ion. Unequal proton and electron numbers create charge.

33. Find the charge when a 2 A current flows for 8 seconds.

    16 C. Using $q = It$: $q = 2 \times 8 = 16$ C.

34. Which particle is transferred during charging by friction?

    Electron. Mobile charged particles that move between objects.

35. Identify the charge of a body when grounded.

    Neutral. Earth connection neutralizes excess charge.

36. What is the role of a grounding wire in charging by induction?

    Provides a path for charge flow. Allows charge to escape to ground.

37. What charge results from removing 7 electrons from a neutral atom?

    Positive. Electron loss leaves positive charge behind.

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