Free Electrostatics MCQs with Answers
831 Electrostatics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Electrostatics describes forces between charges through Coulomb's law, electric fields and field intensity, then uses electric potential to measure energy per unit charge. Capacitors store charge and electrical energy, with capacitance depending on geometry and dielectric material, not simply on the amount of charge present.
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Read the Electrostatics notesFree MDCAT chapter notes with key terms831 questions · page 11 of 42
- A. F/2
- B. 4F
- C. 2F
- D. F/4
Explanation: Coulomb's Law states that the electrostatic force (F) is inversely proportional to the square of the distance (r) between the charges (F ∝…
Correct answer: F/4- A. -10N
- B. +20N
- C. +10N
- D. -20N
Explanation: The new charges are q'₁ = (+3 - 5)µC = -2µC and q'₂ = (+8 - 5)µC = +3µC. The force is proportional to the product of the charges.
Correct answer: -10N- A. Zero
- B. 8N (repulsive)
- C. 8N (attractive)
- D. 16N (attractive)
Explanation: The initial force F is proportional to (2)(6) = 12. After adding -2C, the new charges are 0C and +4C.
Correct answer: Zero- A. εrF
- B. εr/F
- C. F/εr
- D. Fεr
Explanation: The force between charges in a dielectric medium is reduced by a factor equal to the relative permittivity (or dielectric constant) of…
Correct answer: F/εr- A. -8 × 10⁻⁶ J
- B. 8 × 10⁻⁶ J
- C. Zero
- D. 4 × 10⁻⁶ J
Explanation: Potential energy of a dipole is U = -pE cosθ. For θ = 0° (parallel), cosθ = 1, so U = -pE = -(4 × 10⁻¹⁰)(2 × 10⁴) = -8 × 10⁻⁶ J.
Correct answer: -8 × 10⁻⁶ J- A. 3x 10² V m⁻¹
- B. 3×10⁴ V m⁻¹
- C. 3 Vm⁻¹
- D. 3×10⁻⁴ V m⁻¹
Explanation: The electric field (E) between parallel plates is the potential difference (V) divided by the distance (d) between them.
Correct answer: 3×10⁴ V m⁻¹- A. 400 N/C
- B. 800 N/C
- C. 600 N/C
- D. 1200 N/C
Explanation: Electric field intensity (E) from a point charge is inversely proportional to the square of the distance (E ∝ 1/r²).
Correct answer: 800 N/C- A. Zero
- B. 4V
- C. 2.0 V
- D. 16V
Explanation: The potential difference (V) between two points is defined as the work done (W) per unit charge (q). V = W/q = 16.0 J / 4.0 C = 4 V.
Correct answer: 4V- A. 5/3 V
- B. 7/3 V
- C. 3/5 V
- D. 3/7 V
Explanation: Electric potential (V) due to a point charge is inversely proportional to the distance (r) from the charge (V ∝ 1/r).
Correct answer: 5/3 V- A. 9V
- B. 8 x 10⁶ V
- C. 9 x 10⁵ V
- D. 80 V
Explanation: The total charge of the nucleus is Q = Ze = 50 × (1.6 × 10⁻¹⁹ C). The potential is V = kQ/r.
Correct answer: 8 x 10⁶ V- A. VA=VB
- B. VA > VB
- C. VA < VB
- D. Depends upon the material of the sphere
Explanation: For a sphere, the potential on its surface is V = kQ/r. Since both spheres have the same charge (Q), the potential is inversely…
Correct answer: VA > VB212. Two charges +q and -q are situated at a certain distance. At the point exactly midway between them:
- A. Electric field and potential both are zero
- B. Electric field is not zero but potential is not zero
- C. Electric field is zero but potential is not zero
- D. Electric field is not zero but potential is zero
Explanation: The electric field is a vector; at the midpoint, the fields from both charges point in the same direction (from +q to -q) and add up, so…
Correct answer: Electric field is not zero but potential is zero- A. 1.694 x 10⁹ m²
- B. 9.281 x 10⁹ m²
- C. 4.529 x 10⁹ m²
- D. 12.981 x 10⁹ m²
Explanation: The formula for capacitance is C = (kε₀A)/d. Assuming the dielectric is a vacuum (k=1), and rearranging for area gives A = Cd/ε₀.
Correct answer: 1.694 x 10⁹ m²- A. C/4
- B. C/2
- C. 4C
- D. 2C
Explanation: Capacitance is directly proportional to the dielectric constant (k). The ratio of the new capacitance (C') to the old (C) is equal to the…
Correct answer: 4C- A. Increases by a factor of K
- B. Decreases by a factor of K
- C. Increases by a factor of K²
- D. Decreases by a factor of K²
Explanation: Introducing a dielectric material with constant K between the plates of a capacitor increases its ability to store charge.
Correct answer: Increases by a factor of K- A. 2 times
- B. 4 times
- C. 10 times
- D. Remains same
Explanation: The energy (U) stored in a capacitor is given by the formula U = (1/2)CV².
Correct answer: 4 times- A. 4 volts
- B. 2000 volts
- C. 9 volts
- D. 1 volt
Explanation: Using the energy formula U = (1/2)CV², we rearrange to solve for V: V = √(2U/C).
Correct answer: 2000 volts- A. 5µF capacitor
- B. 6µF capacitor
- C. 7µF capacitor
- D. Same potential difference across all
Explanation: In a series circuit, the charge (Q) is the same on all capacitors. The potential difference across a capacitor is given by V = Q/C.
Correct answer: 5µF capacitor- A. Remain the same
- B. Increase
- C. Decrease
- D. Become zero
Explanation: The change in potential energy is ΔU = qΔV. If a positive test charge (q>0) is moved to a higher potential (ΔV>0), the potential energy…
Correct answer: Increase- A. Electric flux
- B. Electric field intensity
- C. Electric potential
- D. All of the above are the same
Explanation: Electric field intensity (or electric field strength) is defined at a point in space as the electrostatic force that would be experienced…
Correct answer: Electric field intensity