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Electric Fields Practice Problems with Solutions - IB Year 13

IB Year 13 | Physics | Electric Fields
Name: _________________________ Date: _________________________ Score: _______ / 40

Two charges of 1 µC and 2 µC, 1 m apart, feel a force of 0.018 N by Coulomb's law with k = 9.0 × 10⁹ N m²/C², and a 0.5 N force on a 2 × 10⁻⁶ C charge means a field of 2.5 × 10⁵ N/C. The key also records 6000 V/m later.

Key Takeaways

Section A: Multiple Choice Questions (1 Mark Each)

Choose the correct option for each question.
1. Two charges, 1 µC and 2 µC, are separated by 1 m. Using k = 9.0 × 10⁹ N m²/C², the force between them is
(a) 0.018 N(b) 0.18 N(c) 1.8 N(d) 18 N
2. A force of 0.5 N acts on a charge of 2 × 10⁻⁶ C. The electric field strength at the charge is
(a) 2.5 × 10⁻⁶ N/C(b) 2.5 × 10⁵ N/C(c) 4 × 10⁻⁶ N/C(d) 0.25 N/C
3. A potential difference of 12 V exists across plates separated by 2 mm. The uniform field strength between the plates is
(a) 600 V/m(b) 6000 V/m(c) 60,000 V/m(d) 24 V/m
4. The direction of the electric field at a point is the direction of the force on
(a) a negative test charge(b) a positive test charge(c) an electron(d) a neutron
5. The magnitude of the charge on an electron is
(a) 1.6 × 10⁻¹⁹ C(b) 1.6 × 10⁻¹⁷ C(c) 9.1 × 10⁻³¹ C(d) 6.02 × 10²³ C
6. A charge of 2 µC moves through a potential difference of 50 V. The work done on the charge is
(a) 1 × 10⁻⁴ J(b) 2.5 × 10⁻⁵ J(c) 1 × 10⁴ J(d) 100 J

Section B: Short Answer Type Questions (2 Marks Each)

Show all steps clearly.
7. Define electric field strength.
8. State the relationship between the electric field strength and the potential difference in a uniform field.
9. State Coulomb's law.
10. Explain what is meant by an equipotential surface.
11. State why the electric field inside a charged conductor in electrostatic equilibrium is zero.
12. A proton moves from a point of lower potential to a point of higher potential. State whether the electric force does positive or negative work on it.
13. State the direction of the electric field between a positive plate and a negative plate.
14. Define the potential difference between two points in an electric field.

Section C: Numericals & Word Problems (3 Marks Each)

Apply the concepts to solve the problems. Show all working.
15. Two charges, each of 2 µC, are separated by 0.1 m. Using F = kq₁q₂ ÷ r² with k = 9.0 × 10⁹ N m²/C², calculate the force between them.
16. Using E = F ÷ q, calculate the electric field strength when a force of 8 × 10⁻⁵ N acts on a charge of 4 × 10⁻⁸ C.
17. Using E = V ÷ d, calculate the field strength when a potential difference of 200 V is applied across plates separated by 0.02 m.
18. Using F = eE with e = 1.6 × 10⁻¹⁹ C, calculate the force on an electron placed in a uniform field of 5000 V/m.
19. Using W = qV with q = 1.6 × 10⁻¹⁹ C, calculate the work done when a proton moves through a potential difference of 100 V.
20. Using E = V ÷ d, calculate the field strength when a potential difference of 24 V is applied across plates separated by 3 cm.

Answer Key

1. a) 0.018 N
2. b) 2.5 × 10⁵ N/C
3. b) 6000 V/m
4. b) a positive test charge
5. a) 1.6 × 10⁻¹⁹ C
6. a) 1 × 10⁻⁴ J
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
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11. Refer to solution guide.
12. Refer to solution guide.
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20. Refer to solution guide.
End of Worksheet

People Also Ask

What force acts between 1 µC and 2 µC separated by 1 m?

0.018 N, option (a) in this worksheet (Q1).

What is the electric field on a 2 × 10⁻⁶ C charge feeling 0.5 N?

2.5 × 10⁵ N/C, option (b) in this worksheet (Q2).

What is the elementary charge recorded in the key?

1.6 × 10⁻¹⁹ C.

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