Two pith balls carrying equal charges are suspended from a common point by strings of equal length, the equilibrium separation between them is \(r\) (as shown in Fig. I). Now, as shown in Fig. II, the strings are rigidly clamped at half the height. The equilibrium separation between the balls now becomes:
     
1. \(\frac{r}{\sqrt[3]{2}}\)
2. \(\frac{r}{\sqrt[2]{2}}\)
3. \(\frac{2r}{3}\)
4. none of the above

A square surface of side \(L\) (m) is in the plane of the paper. A uniform electric field \(\vec{E}\) (V/m), also in the plane of the paper, is limited only to the lower half of the square surface, (see figure). The electric flux in SI units associated with the surface is:     
  

Two parallel infinite line charges with linear charge densities \(+\lambda\) C/m and \(+\lambda\) C/m are placed at a distance \({R}.\) The electric field mid-way between the two line charges is:
1. \(\frac{\lambda}{2 \pi \varepsilon_0 {R}} \) N/C
2. zero
3. \(\frac{2\lambda}{ \pi \varepsilon_0 {R}} \) N/C
4. \(\frac{\lambda}{ \pi \varepsilon_0 {R}}\) N/C

The electric field in a certain region is acting radially outward and is given by \(E=Ar.\) A charge contained in a sphere of radius \(a\) centered at the origin of the field will be given by:
1. \(4 \pi \varepsilon_{{o}} {A}{a}^2\)
2. \(\varepsilon_{{o}} {A} {a}^2\)
3. \(4 \pi \varepsilon_{{o}} {A} {a}^3\)
4. \(\varepsilon_{{o}} {A}{a}^3\)

An electric dipole is placed at an angle of \(30^\circ\) with an electric field intensity \(2\times10^5~ \text{N/C}\). It experiences a torque equal to \(4 ~\text{N-m}\). The charge on the dipole, if the dipole length is \(2~ \text{cm}\), is:

If a charge \(Q\) is situated at the corner of a cube, the electric flux passing through all six faces of the cube is:

If \(10^9\) electrons move out of a body to another body every second, how much time approximately is required to get a total charge of \(1\) C on the other body?
1. \(200\) years
2. \(100\) years
3. \(150\) years
4. \(250\) years

The amount of positive and negative charges in a cup of water (\(250\) g) are respectively:

The ratio of the magnitude of electric force to the magnitude of gravitational force for an electron and a proton will be: (\(m_p=1.67\times10^{-27}~\mathrm{kg}\), \(m_e=9.11\times10^{-31}~\mathrm{kg}\))
1. \(2.4\times10^{39}\)
2. \(2.6\times10^{36}\)
3. \(1.4\times10^{36}\)
4. \(1.6\times10^{39}\)