The electric field at a point on the equatorial plane at a distance \(r\) from the centre of a dipole having dipole moment $\stackrel{}{}$\(\overrightarrow{P}\) is given by:
(\(r\gg\) separation of two charges forming the dipole, \(\epsilon_{0} =\) permittivity of free space) 
1. \(\overrightarrow{E}=\frac{\overrightarrow{P}}{4\pi \epsilon _{0}r^{3}}\) 

2. \(\overrightarrow{E}=\frac{2\overrightarrow{P}}{\pi \epsilon _{0}r^{3}}\)

3. \(\overrightarrow{E}=-\frac{\overrightarrow{P}}{4\pi \epsilon _{0}r^{2}}\)

4. \(\overrightarrow{E}=-\frac{\overrightarrow{P}}{4\pi \epsilon _{0}r^{3}}\)

The acceleration of an electron due to the mutual attraction between the electron and a proton when they are \(1.6~\mathring{A}\) apart is:
( \(\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9~ \text{Nm}^2 \text{C}^{-2}\) )

The electric field at a distance \(\frac{3R}{2}\) from the centre of a charged conducting spherical shell of radius \(R\) is \(E\). The electric field at a distance \(\frac{R}{2}\) from the centre of the sphere is:
1. \(E\)
2. \(\frac{E}{2}\)
3. \(\frac{E}{3}\)
4. zero
 

A hollow conducting sphere of radius \(1~\text{m}\) is given a positive charge of \(10~\mu\text{C}\). The electric field at the centre of the hollow sphere will be:
1. \(60\times10^{3}~\text{Vm}^{-1}\)
2. \(90\times10^{3}~\text{Vm}^{-1}\)
3. zero
4. infinite

The electric field at centre \(O\) of a semicircle of radius \(a\) having linear charge density \(\lambda\) is given by:

     
1. \(\frac{2\lambda}{\epsilon_0 a}\)
2. \(\frac{\lambda\pi}{\epsilon_0 a}\)
3. \(\frac{\lambda}{2\pi \epsilon_0 a}\)
4. \(\frac{\lambda}{\pi \epsilon_0 a}\)
 

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

Who evaluated the mass of electron indirectly with help of charge:
1. Thomson
2. Millikan
3. Rutherford
4. Newton

A charge \(q\) is placed in a uniform electric field \(E.\) If it is released, then the kinetic energy of the charge after travelling distance \(y\) will be:
1. \(qEy\)
2. \(2qEy\)
3. $\frac{qEy}{2}$
4. $\sqrt{qEy}$

The electric field at the equator of a dipole is \(E.\) If the strength of the dipole and distance are now doubled, then the electric field will be:

A point \(Q\) lies on the perpendicular bisector of an electric dipole of dipole moment \(p.\) If the distance of \(Q\) from the dipole is \(r\) (much larger than the size of the dipole), then the electric field at \(Q\) is proportional to:
1. \(p^{2}\) and \(r^{-3}\)
2. \(p\) and \(r^{-2}\)
3. \(p^{-1}\) and \(r^{-2}\)
4. \(p\) and \(r^{-3}\)