A polythene piece rubbed with wool is found to have a negative charge of \(3 \times10^{-7}~\text{C}\). Transfer of mass from wool to polythene is:
1. \(0.7\times10^{-18}~\text{kg}\)
2. \(1.7\times10^{-17}~\text{kg}\)
3. \(0.7\times10^{-17}~\text{kg}\)
4. \(1.7\times10^{-18}~\text{kg}\)

Two insulated charged copper spheres A and B have their centers separated by a distance of 50 cm. What is the mutual force of electrostatic repulsion if the charge on each is  $6.5\times {10}^{-7} C$? The radii of A and B are negligible compared to the distance of separation.
1. 1.52 × 10⁻² N
2. 3.7 × 10⁻² N
3. 2.01 × 10⁻² N
4. 2.23 × 10⁻¹ N

The figure below shows tracks of three charged particles in a uniform electrostatic field. Which particle has the highest charge to the mass ratio?

The electric field at the surface of a black box indicates that the net outward flux through the surface of the box is \(8.0\times10^{3}\) N-m²/C. What is the net charge inside the box?
1. \(1.01\) \(\mu\)C
2. \(0.01\) \(\mu\)C
3. \(0.03\) \(\mu\)C
4. \(0.07\) \(\mu\)C

A point charge \(+ 10 μ\text C\) is at a distance \(5~\text{cm}\) directly above the centre of a square of side \(10~\text{cm},\) as shown in the figure. What is the magnitude of the electric flux through the square?

       
1. \(3.18\times10^5~\text{Nm}^2\text C^{-1}\)
2. \(2.10\times10^5~\text{Nm}^2\text C^{-1}\)
3. \(1.03\times10^5~\text{Nm}^2\text C^{-1}\)
4. \(1.88\times10^5~\text{Nm}^2\text C^{-1}\)

A point charge of 2.0 μC is at the center of a cubic Gaussian surface 9.0 cm on edge. What is the net electric flux through the surface?

1. 2.26 × 10⁵  N  m² C^-1
2. 2.09 × 10⁵  N  m² C^-1
3. 4.33 × 10⁵  N  m² C^-1
4. 4.71 × 10⁵  N  m² C^-1   

A point charge causes an electric flux of \(-1.0\times 10^{3}~\text{Nm}^2/\text{C}\) to pass through a spherical Gaussian surface of \(10.0\) cm radius centered on the charge. If the radius of the Gaussian surface were doubled, how much flux would pass through the surface?
1. \(- 2.0×10^{3}~\text{Nm}^2/\text{C}\)
2. \(- 1.0 ×10^{3}~\text{Nm}^2/\text{C}\)
3. \(2.0 ×10^{3}~\text{Nm}^2/\text{C}\)
4. \(  0\)

A conducting sphere of radius \(10\) cm has an unknown charge. If the electric field, \(20\) cm from the centre of the sphere is \(1.5\times10^3\) N/C and points radially inward, what is the net charge on the sphere?

A uniformly charged conducting sphere of 2.4 m diameter has a surface charge density of $80.0 \mu C/m^2$. The charge on the sphere is:

1. 2 .077 × 10^-3 C
2. 2. 453 × 10^-3C
3. 1. 447 × 10^-3C
4. 3. 461 × 10^-3C