# Electric Flux Density MCQ [Free PDF] – Objective Question Answer for Electric Flux Density Quiz

1. Gauss law is applicable for_________

A. Point charge
B. Sheet charge
C. Line charge
D. Point, sheet, and line charge

Answer: D

Gauss law states that the total electric flux through any closed surface is equal to the charge enclosed by that surface. Hence it applies to all points, surfaces, and volumes.

2. “Total electric flux through any closed surface is equal to the charge enclosed by that surface divided by permittivity”. This is the statement for?

A. Gauss law
B. Lenz law
C. Columb’s law
D. Faraday’s law

Answer: A

The total electric flux through any closed surface is equal to the charge enclosed by that surface divided by permittivity is the statement for Gauss law because, among the four laws, Gauss law deals with electric flux.

3. Electric flux density is a function of_______

A. Volume
B. Charge
C. Current
D. Voltage

Answer: B

Electric flux density is the charge per unit area. Hence it is a function of charge and not any of the other values.

4. As charge increases, what happens to flux density?

A. Increases
B. Decreases
C. Remains constant
D. Becomes zero

Answer: A

Electric flux density is the charge per unit area.

The expression for flux density is:

D = Q/A.

Electric flux is directly proportional to charge, hence as charge increases, electric flux also increases.

5. As the area increases, what happens to electric flux density?

A. Increases
B. Decreases
C. Remains constant
D. Becomes zero

Answer: B

Electric flux density is the charge per unit area.

The expression for flux density is:

D = Q/A.

Electric flux is inversely proportional to area, hence an area increases, electric flux decreases.

6. Which, among the following, is the correct expression for electric flux density?

A. D = ε × E
B. D = ε/E
C. D2 = ε × E
D. D = ε × E2

Answer: A

Electric flux density is directly proportional to the electric field, ε(permittivity of free space) being the constant of proportionality.

Hence D = ε × E.

7. Strength of the electric field is ___________

A. Directly proportional to the force applied
B. Inversely proportional to the force applied
C. Directly proportional to the square of the force applied
D. Inversely proportional to the square of the force applied

Answer: A

Electric field intensity is the force per unit charge, hence it is directly proportional to the force applied.

8. The force applied to a conductor is 10N if the charge in the conductor is 5C, what is the electric field intensity?

A. 10V/m
B. 2V/m
C. 3V/m
D. 15V/m

Answer: B

Electric field intensity is the force per unit charge. The formula is:

E = F/Q = 10/5 = 2V/m.

9. What is the electric flux density in free space if the electric field intensity is 1V/m?

A. 7.76 × 10-12C/m2
B. 8.85 × 10-12C /m2
C. 1.23 × 10-12C /m2
D. 3.43 × 10-12C /m2

Answer: B

The formula for electric filed density is:

D = ε × E = 1 × 8.85 × 10-12

= 8.85 × 10-12C /m2.

10. If the charge in a conductor is 16C and the area of the cross-section is 4m2. Calculate the electric flux density.

A. 64C/m2
B. 16C/m2
C. 4C/m2
D. 2C/m2

Answer: C

Electric Flux density is the charge per unit area. The formula is:

D = Q/A

= 16/4 = 4C/m2.

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