# Electric Charges And Fields MCQs for NEET

A charge is a property associated with the matter due to which it experiences and produces an electric and magnetic field.

• Charges are scalar in nature and they add up like real numbers. (Additivity of Charges)
• The total charge of an isolated system is always conserved. ( Conservation of Charge)
• Charges exist in a discrete amount rather than continuous value. Hence, quantised. (Quantisation of Charge)

1. Which of the following statements is true?

1. The glass rod gives protons to silk, when they are rubbed against each other.
2. The glass rod gives electrons to silk, when they are rubbed against each other.
3. The glass rod gains protons from silk when they are rubbed against each other.
4. The glass rod gains electrons when they are rubbed against each other.

Answer: (c) When a glass rod is rubbed with silk, the rod gives electrons to silk.

2. Two spheres with charges +Q and -Q are placed at a certain distance from each other. A force F acts between the two spheres. If a third sphere with charge Q is kept between them, it experiences a force in magnitude and direction as

1. 3F in the direction of +Q charge
2. 4F in the direction of +Q charge
3. 8F in the direction of -Q charge
4. Zero having no direction

Answer: (b) 8F towards -Q charge

3. At the four corners of the square A, B, C and D, Four charges of equal magnitude q are placed. Determine the magnitude of the force acting on the charge at point B?

1. $\frac{(\frac{2+1}{\sqrt{2}})q^2}{4\pi \varepsilon _0a^2}$
2. $\frac{(1+2\sqrt{2})q^2}{2\times 4\pi \epsilon _0a^2}$
3. $\frac{4q^2}{4\pi \epsilon _0a^2}$
4. $\frac{3q^2}{4\pi \epsilon _0a^2}$

Answer: (b) $\frac{(1+2\sqrt{2})q^2}{2\times 4\pi \epsilon _0a^2}$

4. At a distance r, two equal charges are kept and they exert a force F on each other. What is the force acting on each charge, if the distance between them are doubled and charges are halved?

1. 4 F
2. F/8
3. F/4
4. F/16

5. Determine the total electric flux of a unit positive charge which is kept in the air?

1. ${\epsilon _0}^{-1}$
2. ${\epsilon _0}$
3. $4\pi \epsilon _0$
4. ${4\pi \epsilon _0}^{-1}$

Answer: (d) ${4\pi \epsilon _0}^{-1}$

6. The variation of electric field E due to a hollow spherical conductor of radius R as a function of distance from the centre of the sphere is shown in which of the following graphs?

7. Which of the following statement is true?

1. The electric field at a point is always constant.
2. The electric field at a point is constant if a charge is present at the point.
3. The electric field at a point is not constant a negative charge is present at the point.
4. The electric field at a point is not constant if there is a charge at that point.

Answer: (d) The electric field at a point is discontinuous if there is a charge at that point.

8. Gauss law will not be true if

1. the speed of light isn’t a universal constant
2. the inverse square law is false
3. there are magnetic monopoles
4. None of the above

Answer: (b) the inverse square law is not true

9. What is the Si unit of permittivity of free space?

1. Weber
3. C2N-1m-2
4. C2N-1m-2

10. Which of the following statements is true?

1. Electric field lines provide information about the direction of the electric field
2. Electric field lines provide information about the field strength
3. Electric field lines provide information about the type of charge
4. All of the above

Answer: (d) All of the above

11. The electric field lines due to a single negative charge is represented by