Electrostatics Practice Test 2

1.

Two point charges, +4 μC and +6 μC, are placed 0.3 m apart in vacuum. What is the magnitude of the force between them? (k = 9 × 10⁹ N·m²/C²)

a) 0.8 N b) 2.4 N c) 7.2 N d) 0.12 N

2.

What is the net electric field at the midpoint between two equal but opposite point charges +Q and -Q separated by distance 2a?

a) Zero b) \( \frac{2kQ}{a^2} \) directed from +Q to -Q c) \( \frac{4kQ}{a^2} \) directed from -Q to +Q d) \( \frac{kQ}{a^2} \) directed from +Q to -Q

3.

Which of the following statements is true about the electric field inside a conductor in electrostatic equilibrium?

a) It is always zero b) It is maximum at the center c) It is equal to the field at the surface d) It depends on the shape

4.

What is the electric potential at the center of a square of side a with four equal charges +Q at each corner?

a) Zero b) \( \frac{4kQ}{a} \) c) \( \frac{2kQ}{a} \) d) \( \frac{4kQ}{a\sqrt{2}} \)

5.

A conducting sphere of radius R carries a net charge Q. What is the electric field at a distance r = 2R from the center?

a) \( \frac{kQ}{R^2} \) b) \( \frac{kQ}{4R^2} \) c) \( \frac{kQ}{2R^2} \) d) Zero

6.

What is the electric field inside a uniformly charged solid sphere of radius R and total charge Q at a distance r < R from the center?

a) \( \frac{kQr}{R^3} \) b) \( \frac{kQ}{r^2} \) c) \( \frac{kQ}{R^2} \) d) Zero

7.

Two point charges, +Q and +Q, are placed a distance d apart. Where is the electric field zero along the line joining them?

a) At the midpoint b) At a point outside the segment, beyond either charge c) There is no such point d) At a point between the charges, but not at the midpoint

8.

A 1 μC charge is placed at the origin. What is the electric potential at a point 0.5 m away? (k = 9 × 10⁹ N·m²/C²)

a) 1.8 × 10⁴ V b) 9 × 10³ V c) 2 × 10⁴ V d) 1.2 × 10⁴ V

9.

What is the work required to move a 2 μC charge from infinity to a point 0.2 m from a 5 μC point charge? (k = 9 × 10⁹ N·m²/C²)

a) 0.45 J b) 0.9 J c) 1.8 J d) 0.18 J

10.

Which of the following is true about the electric field at the center of a uniformly charged ring?

a) It is maximum b) It is zero c) It is equal to the field at the edge d) It depends on the total charge

11.

Using Gauss's law, what is the electric field just outside the surface of a uniformly charged conducting sphere of radius R and total charge Q?

a) \( \frac{kQ}{R^2} \) b) \( \frac{kQ}{2R^2} \) c) \( \frac{kQ}{R} \) d) Zero

12.

Which of the following best describes the direction of electric field lines at the surface of a charged conductor?

a) Perpendicular to the surface b) Tangential to the surface c) At an angle of 45° d) Randomly oriented

13.

Which of the following is true about the electric field inside a parallel-plate capacitor (neglecting edge effects)?

a) It is uniform and points from positive to negative plate b) It is zero everywhere c) It is strongest near the edges d) It points from negative to positive plate

14.

Which of the following materials is an electrical insulator?

a) Copper b) Silver c) Aluminum d) Glass

15.

What happens to the electric field inside a conductor when it reaches electrostatic equilibrium?

a) It becomes zero b) It becomes maximum c) It points outward d) It oscillates

16.

What is the potential difference between two points 0.2 m apart in a uniform electric field of 400 V/m?

a) 80 V b) 200 V c) 20 V d) 2 V

17.

A 3 μC charge is placed in an electric field of 2 × 10⁴ N/C. What is the force on the charge?

a) 0.06 N b) 0.6 N c) 6 N d) 0.006 N

18.

What is the energy stored in a 2 μF capacitor charged to 100 V?

a) 0.01 J b) 0.02 J c) 0.005 J d) 0.5 J

19.

Two point charges, +2 μC and -2 μC, are 0.1 m apart. What is the potential energy of the system? (k = 9 × 10⁹ N·m²/C²)

a) -3.6 J b) 3.6 J c) -1.8 J d) 1.8 J

20.

What is the electric field 0.2 m away from a long straight wire carrying a uniform linear charge density of 5 × 10^-6 C/m? (\( \varepsilon_0 = 8.85 \times 10^{-12} \) C²/N·m²)

a) 1.1 × 10⁵ N/C b) 4.5 × 10⁵ N/C c) 3.6 × 10⁵ N/C d) 2.8 × 10⁵ N/C

21.

Which of the following statements about electric field lines is correct?

a) They can cross each other b) They begin on negative charges and end on positive charges c) Their density represents field strength d) They form closed loops in electrostatics

22.

What happens to the electric field inside a hollow, uncharged, conducting shell when a point charge is placed outside the shell?

a) It becomes nonzero b) It remains zero c) It oscillates d) It points toward the shell

23.

Which of the following is true about the potential difference between any two points on a conductor in electrostatic equilibrium?

a) It is always positive b) It is always negative c) It is zero d) It depends on the shape

24.

Which of the following best describes the effect of inserting a dielectric between the plates of a charged, isolated capacitor?

a) The capacitance decreases b) The stored energy increases c) The voltage across the plates decreases d) The charge on the plates increases

25.

Which of the following is true about the electric field at the surface of a conductor with a sharp point?

a) It is weaker than at a flat surface b) It is the same as at a flat surface c) It is stronger than at a flat surface d) It is always zero

26.

Which of the following is true about the net electric flux through a closed surface that encloses equal amounts of positive and negative charge?

a) It is positive b) It is negative c) It is zero d) It depends on the surface area

27.

A 5 μC charge is placed at the center of a cube of side 0.1 m. What is the electric flux through one face of the cube? (\( \varepsilon_0 = 8.85 \times 10^{-12} \) C²/N·m²)

a) 9.4 × 10⁴ N·m²/C b) 4.7 × 10⁴ N·m²/C c) 1.5 × 10⁵ N·m²/C d) 7.5 × 10⁴ N·m²/C

28.

Two point charges, +Q and +2Q, are placed 1 m apart. Where along the line joining them is the electric field zero? (Assume Q > 0)

a) 0.33 m from +Q, on the side away from +2Q b) 0.67 m from +Q, between the charges c) 2 m from +Q, on the side away from +2Q d) 0.5 m from +Q, between the charges

29.

What is the minimum work required to assemble three point charges, each of +1 μC, at the corners of an equilateral triangle of side 0.2 m? (k = 9 × 10⁹ N·m²/C²)

a) 0.27 J b) 0.41 J c) 0.54 J d) 0.81 J

30.

A parallel-plate capacitor has plates of area 0.01 m² separated by 1 mm and is filled with a dielectric of constant 5. If the voltage across the plates is 100 V, what is the charge stored? (\( \varepsilon_0 = 8.85 \times 10^{-12} \) C²/N·m²)

a) 4.4 × 10^-8 C b) 2.2 × 10^-8 C c) 8.9 × 10^-8 C d) 1.8 × 10^-8 C

Electrostatics Practice Test 2

30 Questions – AP Physics C Level