# Objective Questions on Electrostatic Field

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## Objective Questions on Electrostatic Field

Objective Questions on Electrostatic Field, MCQ on electric charges and fields, MCQ on electrostatics, electric field multiple-choice question ans answer.

### Multiple Choice Questions

1. The proportionality constant in Coulomb’s law has unit of
• Newton

2. The value of proportionality constant in Coulomb’s law is

• 9 × 109
• 9 × 10–9
• 8.854 × 10–12
• 1/36 π × 109

Answer: 9 × 109

3. The force magnitude between Q1 = 1C and Q2 = 1C when they are separated by 1 m in free space is

• 9 × 109 N
• 8.854 × 10–12 N
• 1/36 π × 10-9 N
• 9 × 10–9 N

Answer: 9 × 109 N

4. Potential has the unit of

• Joules/Coulomb
• Joules
• Joules/m3
• Joules/m2

5. The unit of electric flux is

• Coulomb
• Coulomb/metre
• Weber
• Weber/m2

6. The unit of electric field is

• Newton
• Coulomb/Newton
• Newton/Coulomb
• Coulomb/metre

7. Potential at all the points on the surface of a conductor is

• the same
• not the same
• zero
• infinity

8. Gradient of the potential and an equipotential surface

• have the same direction
• have opposite directions
• are orthogonal to each other
• have no directional relation

Answer: are orthogonal to each other

9. The Laplacian operator, ∇2

• has unit of m2
• is a vector operator
• has unit of 1/m2
• has no unit

Answer: has unit of 1/m2

10. Laplace’s equation has

• two solutions
• infinite solutions
• no solution
• only one solution

Answer: only one solution

11. The surface charge density in a good dielectric is

• zero
• ρs
• infinity
• – ρs

12. Gauss’s law in point form is

• $\bigtriangledown .D=\rho _{\upsilon }$
• $\bigtriangledown .D=\rho _{s}$
• $\bigtriangledown .D=Q$
• $\bigtriangledown D=\rho _{\upsilon }$

Answer: $\bigtriangledown .D=\rho _{\upsilon }$

13. Poisson’s equation is

• $\bigtriangledown ^{2}V=\rho _{\upsilon}/\epsilon$
• $\bigtriangledown ^{2}V=-\rho _{\upsilon}/\epsilon$
• $\bigtriangledown ^{2}V=-\rho _{\upsilon}$
• $\bigtriangledown ^{2}V=-\dot{\rho _{\upsilon}}/\epsilon$

Answer: $\bigtriangledown ^{2}V=-\rho _{\upsilon}/\epsilon$

14. Electric flux lines

• originate at (+)ve charge
• originate at (–)ve charge
• are closed loops
• originate at (+)ve charge and also terminate at (+)ve charge

Answer: originate at (+)ve charge

15. Unit of electric flux is

• Coulomb
• Weber
• Tesla
• Weber/m