Three charges 4q, Q, and q are in a straight line in the position of 0, l/2, and l respectively. The resultant force on q will be zero if Q = 

(1) – q

(2) –2q

(3) $-\frac{q}{2}$

(4) 4q

Two small spheres each having the charge +Q are suspended by insulating threads of length L from a hook. If this arrangement is taken in space where there is no gravitational effect, then the angle between the two suspensions and the tension in each will be:

1. ${180}^o,\frac{1}{4\pi {\epsilon }_0}\frac{Q^2}{{\left(2L\right)}^2}$

2. ${90}^o,\frac{1}{4\pi {\epsilon }_0}\frac{Q^2}{L^2}$

3. ${180}^o,\frac{1}{4\pi {\epsilon }_0}\frac{Q^2}{2L^2}$

4. ${180}^o,\frac{1}{4\pi {\epsilon }_0}\frac{Q^2}{L^2}$ 

Two charges each of 1 coulomb are at a distance 1 km apart, the force between them is 

(1) 9 × 10³ Newton

(2) 9 × 10^–3 Newton

(3) 1.1 × 10^–4 Newton

(4) 10⁴ Newton

Two charges +2 C and +6 C are repelling each other with a force of 12 N. If each charge is given –2 C of charge, then the value of the force will be:

1. 4 N (Attractive)

2. 4 N (Repulsive)

3. 8 N (Repulsive)

4. Zero

The dielectric constant of pure water is 81. Its permittivity will be 

(1) 6.91 × 10^–10 MKS units

(2) 8.86 × 10^–12 MKS units

(3) 1.02 × 10¹³ MKS units

(4) Cannot be calculated

Force of attraction between two point charges Q and – Q separated by d meter is F_e. When these charges are given to two identical spheres of radius R = 0.3 d whose centres are d meter apart, the force of attraction between them is 

(1) Greater than F_e

(2) Equal to F_e

(3) Less than F_e

(4) None of the above

One metallic sphere A is given a positive charge whereas another identical metallic sphere B of the exact same mass as of A is given an equal amount of negative charge. Then:

(1) mass of A and mass of B are the same.

(2) mass of A is more.

(3) mass of B is less.

(4) mass of B is more.

The force between two charges 0.06 m apart is 5 N. If each charge is moved towards the other by 0.01 m, then the force between them will become:

1. 7.20 N

2. 11.25 N

3. 22.50 N

4. 45.00 N

When 10¹⁹ electrons are removed from a neutral metal plate, the electric charge on it is?
1. –1.6 C
2. +1.6 C
3. 10⁺¹⁹ C
4. 10^–19 C

Two charges each equal to 2μC are 0.5m apart. If both of them exist inside the vacuum, then the force between them is 

(1) 1.89 N

(2) 2.44 N

(3) 0.144 N

(4) 3.144 N